Почему я получаю ошибку "SendCommand не был объявлен"

#include <Adafruit_Fingerprint.h>
#include  <SoftwareSerial.h>
#include <LiquidCrystal.h>

uint8_t id;
int getFingerprintIDez();
//pin #16 is IN from sensor (GREEN wire)
//pin #15 is OUT from arduino (WHITE wire)
int Contrast = 100;
SoftwareSerial mySerial(52, 16);
LiquidCrystal lcd(13, 12, 11, 10, 9, 8); // initialize the library with the numbers of the interface pins
Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial);
#define S1 22 //Button candidate A
#define S2 24 // Button candidate B
#define S3 26 // Button candidate c
#define S4 28 // Button candidate D
#define S5 30 // Button Result
#define S6 2 // Button submit
#define S7 32 // Button to cast vote
int can1 = 0;
int can2 = 0;
int can3 = 0;
int can4 = 0;
int total;
SoftwareSerial ESP8266(50, 18);// RX, TX

void setup() { 
  Serial.begin(9600); // initialize the serial communications:
  lcd.begin(16, 2); lcd.clear();
  lcd.print("  Polling Day  ");
  lcd.setCursor(0, 1);
  lcd.print("      UPM      ");
  delay(2000);

  mainpage();

  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(A0, INPUT);

  finger.begin(57600); // set the data rate for the sensor serial port

  pinMode(S1, INPUT);
  pinMode(S2, INPUT);
  pinMode(S3, INPUT);
  pinMode(S4, INPUT);
  pinMode(S5, INPUT);
  pinMode(S6, INPUT);
  pinMode(S7, INPUT);

  ESP8266.begin(9600);

  digitalWrite(S1, HIGH);
  digitalWrite(S2, HIGH);
  digitalWrite(S3, HIGH);
  digitalWrite(S4, HIGH);
  digitalWrite(S5, HIGH);
  digitalWrite(S6, HIGH);
  digitalWrite(S7, HIGH);

  SendCommand("AT+RST", "Ready");
  delay(5000);
  SendCommand("AT+CWMODE=1", "OK");
  SendCommand("AT+CIFSR", "OK");
  SendCommand("AT+CIPMUX=1", "OK");
  SendCommand("AT+CIPSERVER=1,80", "OK");
}

void loop() {// run over and over again
  getFingerprintID();
  delay(100);
  digitalWrite (13, HIGH);
  if (digitalRead(S5) == 0) { // To view the result for admin only
    int total = can1 + can2 + can3 + can4;
    lcd.clear();
    lcd.setCursor(1, 0);
    lcd.print("1");
    lcd.setCursor(1, 1);
    lcd.print(can1);
    lcd.setCursor(5, 0);
    lcd.print("2");
    lcd.setCursor(5, 1);
    lcd.print(can2);
    lcd.setCursor(9, 0);
    lcd.print("3");
    lcd.setCursor(9, 1);
    lcd.print(can3);
    lcd.setCursor(13, 0);
    lcd.print("4");
    lcd.setCursor(13, 1);
    lcd.print(can4);
    delay(4000);
    if (total) {
      if ((can1 > can2 && can1 > can3 && can1 > can4)) {
        lcd.clear();
        lcd.print("Can A is Winner");
        delay(3000);
        lcd.clear();
      } else if ((can2 > can1 && can2 > can3 && can2 > can4)) {
        lcd.clear();
        lcd.print("Can B is Winner");
        delay(3000);
        lcd.clear();
      } else if ((can3 > can1 && can3 > can2 && can3 > can4)) {
        lcd.clear();
        lcd.print("Can C is Winner");
        delay(3000);
        lcd.clear();
      } else if (can4 > can1 && can4 > can2 && can4 > can3) {
        lcd.setCursor(0, 0);
        lcd.clear();
        lcd.print("Can D is Winner");
        delay(3000);
        lcd.clear();
      } else if (can4 > can1 && can4 > can2 && can4 > can3) {
        lcd.setCursor(0, 0);
        lcd.clear();
        lcd.print("Can D is Winner");
        delay(3000);
        lcd.clear();
      } else {
        lcd.clear();
        lcd.print(" Tie Up Or ");
        lcd.setCursor(0, 1);
        lcd.print(" No Result ");
        delay(3000);
        lcd.clear();
      }
    } else {
      lcd.clear();
      lcd.print("No Voting....");
      delay(3000);
      lcd.clear();
    }
    can1 = 0; can2 = 0; can3 = 0; can4 = 0, total = 0;
    lcd.clear();
    adminpage();
  }

  if (digitalRead(S7) == 0) { //To cast avote for user
    voterpage();
  }

  if (digitalRead(S1) == 0) {
    can1++;
    votereceived();
    mainpage();
  }

  while (digitalRead(S1) == 0);
  if (digitalRead(S2) == 0) {
    can2++;
    votereceived();
    mainpage();
  }
  while (digitalRead(S2) == 0);
  if (digitalRead(S3) == 0) {
    can3++;
    votereceived();
    mainpage();
  }
  while (digitalRead(S3) == 0);
  if (digitalRead(S4) == 0) {
    can4++;
    votereceived();
    mainpage();
  }
  while (digitalRead(S4) == 0);
  if (digitalRead(S6) == 0) {
    lcd.clear();
    lcd.print("Submitting...");
    delay(1000);
    ESP8266.println("AT+CIPSEND=0,23");
    delay(1000);
    SendCommand("AT+CIPCLOSE=0", "OK");
  }
  String IncomingString = "";
  boolean StringReady = false;

  while (ESP8266.available()) {
    IncomingString = ESP8266.readString();
    StringReady = true;
  }

  if (StringReady) {
    Serial.println("Received String: " + IncomingString);

    if (IncomingString.indexOf("LED=ON") != -1) {
      digitalWrite(LED, HIGH);
    }

    if (IncomingString.indexOf("LED=OFF") != -1) {
      digitalWrite(LED, LOW);
    }
  }

  boolean SendCommand(String cmd, String ack) {
    ESP8266.println(cmd); // Send "AT+" command to module
    if (!echoFind(ack)) // timed out waiting for ack string
      return true; // ack blank or ack found
  }

  boolean echoFind(String keyword) {
    byte current_char = 0;
    byte keyword_length = keyword.length();
    long deadline = millis() + TIMEOUT;
    while (millis() < deadline) {
      if (ESP8266.available()) {
        char ch = ESP8266.read();
        Serial.write(ch);
        if (ch == keyword[current_char])
          if (++current_char == keyword_length) {
            Serial.println();
            return true;
          }
      }
    }
    return false; // Timed out
  }
}

uint8_t getFingerprintID() { 
  uint8_t p = finger.getImage();
  switch (p) {
    case FINGERPRINT_OK:
      lcd.clear();
      lcd.print(" Image taken... ");
      delay(1000);
      break;
    case FINGERPRINT_NOFINGER:
      return p;
    case FINGERPRINT_PACKETRECIEVEERR:
      return p;
    case FINGERPRINT_IMAGEFAIL:
      return p;
    default:
      return p;
  }

  // OK success!
  p = finger.image2Tz();
  switch (p) {
    case FINGERPRINT_OK:
      break;
    case FINGERPRINT_IMAGEMESS:
      return p;
    case FINGERPRINT_PACKETRECIEVEERR:
      return p;
    case FINGERPRINT_FEATUREFAIL:
      return p;
    case FINGERPRINT_INVALIDIMAGE:
      return p;
    default:
      return p;
  }

  // OK converted!
  p = finger.fingerFastSearch();
  if (p == FINGERPRINT_OK) {
    if (finger.fingerID == 26) {
      lcd.clear();
      lcd.setCursor(1, 0);
      lcd.print("Redirecting to");
      lcd.setCursor(1, 1);
      lcd.print("Admin process");
    } else {
      lcd.clear();
      lcd.setCursor(2, 0);
      lcd.print("Valid Voter!");
      lcd.setCursor(2, 1);
      lcd.print("ID : ");
      lcd.print(finger.fingerID);
    }

    digitalWrite(11, HIGH);
    delay(1000);
    digitalWrite(11, LOW); // turn on green LED to indicate match
  } else if (p == FINGERPRINT_NOTFOUND) {
    lcd.clear();
    lcd.setCursor(1, 0);
    lcd.print("Unregistered");
    lcd.setCursor(3, 1);
    lcd.print("Voter!");
    delay(1000);
    lcd.clear();
    lcd.setCursor(2, 0);
    lcd.print("scan finger");
    lcd.setCursor(6, 1);
    lcd.print("again");
    return p;
  } else {
    return p;
  }

  // IF FOUND A MATCH............
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Found ID #");

  if (finger.fingerID == 26) {
    adminpage();
  } else {
    voterpage();
  }
}

// returns -1 if failed, otherwise returns ID #
int getFingerprintIDez() {
  uint8_t p = finger.getImage();
  if (p != FINGERPRINT_OK) return -1;
  p = finger.image2Tz();
  if (p != FINGERPRINT_OK) return -1;
  p = finger.fingerFastSearch();
  if (p != FINGERPRINT_OK) return -1;
  // found a match!
  digitalWrite(13, LOW);
  delay(10);
  digitalWrite(13, HIGH);
  delay(10);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Found ID # ");
  lcd.print(finger.fingerID);
  lcd.setCursor(0, 1);
  lcd.print("confidence ");
  lcd.print(finger.confidence);
  return finger.fingerID;
}

void voterpage() {
  lcd.clear();
  lcd.setCursor(1, 0);
  lcd.print("Candidate 1");
  lcd.setCursor(1, 1);
  lcd.print("Mohd Faiz");
  delay(3000);
  lcd.clear();
  lcd.setCursor(1, 0);
  lcd.print("Candidate 2");
  lcd.setCursor(1, 1);
  lcd.print("Siti Nur Ila");
  delay(3000);
  lcd.clear();
  lcd.setCursor(1, 0);
  lcd.print("Candidate 3");
  lcd.setCursor(1, 1);
  lcd.print("Muhammad Aus");
  delay(3000);
  lcd.clear();
  lcd.setCursor(1, 0);
  lcd.print("Candidate 4");
  lcd.setCursor(1, 1);
  lcd.print("Wan zakaria");
  delay(3000);
  lcd.clear();
  lcd.setCursor(1, 0);
  lcd.print("Choose 1 only");
  lcd.setCursor(1, 1);
  lcd.print("1");
  lcd.setCursor(5, 1);
  lcd.print("2");
  lcd.setCursor(9, 1);
  lcd.print("3");
  lcd.setCursor(13, 1);
  lcd.print("4");
}

void votereceived() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Vote Received");
  lcd.setCursor(2, 1);
  lcd.print("Thank You :)");
  delay(2000);
}

void adminpage() {
  lcd.clear();
  lcd.setCursor(3, 0);
  lcd.print("1");
  lcd.setCursor(1, 1);
  lcd.print("Result");
  lcd.setCursor(11, 0);
  lcd.print("2");
  lcd.setCursor(8, 1);
  lcd.print(" Submit");
  delay(2000);
}

void mainpage() {
  lcd.clear(); lcd.setCursor(0, 0); lcd.print("Scan your finger");
}