Map is not working after installing from play store in android

I'm stuck in this issue, when i run my project in eclipse it shows map correct, but when i upload it to Google play store and when i install it in my device , it shows the blank map, I don't know what is a problem my map key is correct, package name is correct, i also generate new map key and try, but it also doesn't work. I don't know where is the issue.