Grove Speech Recognizer with Arduino Mega 2560

Hello everbody.
First I worked with the Arduino Uno and the Grove Speech Recognizer, everything fine.
Now I need the Arduino Mega for my project. I have trouble connecting the Grove Speech Recognizer.
The serial communivation doesn’t work (I have tried pins 0 and 1 which are for
serial communication and also tried pins 2 and 3). I can compile everything but the Grove Speech Recognizer doesn’t communicate with my Mega. It receives and it repeats my orders as usual
but there is no following action. Also I didn’t receive any fail Messages, I can compile everything.

Does someone know which pins to use in order with the Arduino Mega?

Thanks in advance.