How to get Parallax PMB-648 GPS module working with Arduino UNO?

Good day!
Is it possible to use Arduino Mega instead of Ardino Uno? To be honest I tried to use Mega with serial pin dig 15 (RX) instead of dig pin 6 in Uno... But Nothing ( I didnt get data . If I use with Uno and pin 6 I can get data.... If somebody knows what is the problem...pls help