expected primary-expression before '(' token error

I cannot find where the missing bracket should be. Can anyone help?

Code:
#include <Keypad.h>
#include <LiquidCrystal.h>
#include <Servo.h>

Servo myservo;
LiquidCrystal led(A0, A1, A2, A3, A4, A5);

#define passwordLength 7

int servoPos = 0;

char data[passwordLength];
char master[passwordLength] = "000000";
byte data_count = 0, master_counter = 0;
bool passwordAccepted;
char customKey;

const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

bool servo = true;

byte rowPins[ROWS] = {0, 1, 2, 3};
byte colPins[COLS] = {4, 5, 6, 7};

Keypad customKeypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);


void setup() {
  Serial.begin(9600);

}

void loop() {
  if (servo == 0){
    customKey = customKeypad.getKey();
    if (customKey == '#'){
      Serial.println(String("HASH HAS BEEN PRESSED, THIS WOULD OPEN THE DOOR ONCE THE CODE HAS BEEN ENTERED"));
    }
  }
  else Open();
}
void clearData(){
  while (data_count != 0){
    data[data_count--] = 0;
  }
  return;
}

void ServoOpen(){
  for (servoPos = 180; servoPos >= 0; servoPos++) {
    Serial.println(String("The servo postion in degree is: " + servoPos +));
  }
}

void ServoClose(){
   for (servoPos = 0; servoPos <= 180; servoPos--) {
    Serial.println(String("The servo postion in degree is: " + servoPos +));
  }
}

void Open(){
  customKey = customKeypad.getKey();
  if (customKey){
    Serial.println(String("Key pressed: " + customKey +));
  }
}

What is the last '+' in this line for?

    Serial.println(String("Key pressed: " + customKey + ));

wildbill:
What is the last '+' in this line for?

    Serial.println(String("Key pressed: " + customKey + ));

To print to the serial monitor what key has been pressed, I am just making that the keys pressed match up.

This does that:

    Serial.println(String("Key pressed: " + customKey ));

What you have has an extra '+':

    Serial.println(String("Key pressed: " + customKey + ));

The compiler is saying (cryptically) "Plus what?".

Same thing further up too.