I had use GCM service on my app , I did my code after more resarches also from stack overflow members , and when I try to test the code on my emulator I didn\'t find any reg
add google account to your emulator: setting->account&sync-> Add account (from @curious_mind comment)
If the emulator is running Android 4.0.4 or later, this step is optional as GCM does not require an account from this version on.
for me it fixed the problem.