SIM800l with arduino mega problem

Hello,

I am receiving some kind of an error loop when i am trying to execute manual AT commands in the serial monitor.

I just want to send a SMS to a number and my connections between Arduino and the module are: Arduino -> SIM800l

GND->GND 5V->VCC Rx2->TX Tx2->RX

Exemple:

at -> ok at+cmgf=1 -> ok at+cmgs="+407xxxxxxxx" -> ? and here it stops....

Below is the code that i am using and i am sorry if it is not put with the right format.

void setup() {
 Serial.begin(115200);
  Serial2.begin(115200);
}

void loop() {

 while(Serial2.available()){
  Serial.write(Serial2.read());
 }

  
 while(Serial.available()){
  Serial2.write(Serial.read());
 }

}

After i made more testes, i am receiving when i am entering at+cmgf=1 -> ERROR, but at+cmgf? it is working and i am receiving that +cmgf=0. Can you please help me?