strcmp brakes Arduino sketch - c++

Question

For a school project, I'm using an Arduino Uno together with a Parallax RFID, a LCD screen and an esp8226-wifi module.
I'm trying to compare the scanned tag with the tags in the database and send the name of the tag owner to a terminal in the Blynk app. Everything works just fine until I put in the function that compares the tags. If I do that, everything stops working, even the code in the setup() part. How can I fix this?
I think the problem has somehing to do with the strcmp.
/* Libraries that need to be manually installed:
Blynk libraries: https://github.com/blynkkk/blynk-library/releases/download/v0.5.0/Blynk_Release_v0.5.0.zip
LiquidCrystal_I2C library: https://cdn.instructables.com/ORIG/FVH/K8OQ/J8UH0B9U/FVHK8OQJ8UH0B9U.zip
*/
#define BLYNK_PRINT Serial
#include <SoftwareSerial.h>
#include <ESP8266_Lib.h>
#include <BlynkSimpleShieldEsp8266.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
//Setting up the Blynk wifi connection
#define ESP8266_BAUD 9600
char auth[] = "87b00838cd834e4e87a0422265cc7a9e";
char ssid[] = "bbox2-56b2";
char pass[] = "91C2D797F6";
//Setting up the virtual pins
WidgetTerminal terminal(V1);
BLYNK_WRITE(V1){}
//Setting up the RFID
#define RFIDEnablePin 8
#define RFIDSerialRate 2400
String RFIDTAG=""; //Holds the RFID Code read from a tag
String DisplayTAG = ""; //Holds the last displayed RFID Tag
//Setting up the LCD
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
//Setting up the serial connection
SoftwareSerial EspSerial(2, 3);
ESP8266 wifi(&EspSerial);
void setup()
{
//Serial communication
Serial.begin(RFIDSerialRate);
EspSerial.begin(ESP8266_BAUD);
Serial.begin(RFIDSerialRate);
delay(10);
//Blynk setup
Blynk.begin(auth, wifi, ssid, pass);
//LCD setup
lcd.begin(16,2);//16 kolommen, 2 rijen
lcd.backlight();
//RFID setup
pinMode(RFIDEnablePin,OUTPUT);
digitalWrite(RFIDEnablePin, LOW);
terminal.println("Terminal printing succesfull");
terminal.flush();
}
void loop()
{
if(Serial.available() > 0)
{
ReadSerial(RFIDTAG);
}
if(DisplayTAG!=RFIDTAG)
{
DisplayTAG=RFIDTAG;
// PROBLEM STARTS HERE
//Tag database
char tags[10][10] = {"6196", "6753", "5655", "69EC", "9FFC"};
char owners[10][30] = {"per1", "per2", "per3", "per4", "per5"};
int i = 0;
int j = 0;
int ownerLength = 0;
char lastTag[10];
RFIDTAG.toCharArray(lastTag, 10);
while (i < 10)
{
if (strcmp(tags[i], lastTag) == 0)
{
ownerLength = strlen(owners[i]);
while (j < ownerLength)
{
terminal.print(owners[i][j]);
}
terminal.println("has entered the parking\n\r");
terminal.flush();
break;
}
i++;
}
i = 0;
j = 0;
//PROBLEM ENDS HERE
lcd.clear();
lcd.setCursor(0,0);
lcd.print("Last tag:");
lcd.setCursor(0,1);
lcd.print(RFIDTAG);
digitalWrite(RFIDEnablePin, HIGH);
delay(1000);
digitalWrite(RFIDEnablePin, LOW);
}
Blynk.run();
}
//Function for reading the tag
void ReadSerial(String &ReadTagString)
{
int bytesread = 0;
int val = 0;
char code[10];
String TagCode="";
if(Serial.available() > 0)
{
if((val = Serial.read()) == 10)
{
bytesread = 0;
while(bytesread<10) // Reads the tag code
{
if( Serial.available() > 0)
{
val = Serial.read();
if((val == 10)||(val == 13)) // If header or stop bytes before the 10 digit reading
{
break; // Stop reading
}
code[bytesread] = val; // Add the digit
bytesread++; // Ready to read next digit
}
}
if(bytesread == 10) // If 10 digit read is complete
{
for(int x=6;x<10;x++) //Copy the Chars to a String
{
TagCode += code[x];
}
ReadTagString = TagCode; //Returns the tag ID
while(Serial.available() > 0) //Burn off any characters still in the buffer
{
Serial.read();
}
}
bytesread = 0;
TagCode="";
}
}
}