NRF24L01: Always receiving an "0" at the end of transmission

Robin2:
Post the program with that change.

...R

If I add a delay of for example 1 millisecond, the "0" disappears in the Serial Monitor.
But I don't understand why there is a delay needed...

void loop(void){
  //check if data available
  if (radio.available()){
      //read data from nrf24l01 buffer
      radio.read(&rxTxData, sizeof(long));
      Serial.println(rxTxData);
   }
   delay(1);
}