If you had unspent Glu Credits in your account that suddenly dropped to zero, OR if your gameplay is not adding currency gained during gameplay, make sure you are playing while connected to a reliable Wi-Fi. If the problem remains, your device may not be communicating to our servers. Here is how to resolve the problem:
 
Using a file manager, locate the folder on your device under:
sdcard0/Androi/data/com.glu.android.gwallet
 
Delete this folder “com.glu.android.gwallet” to force the game to re-create the folder next time it is launched. This re-establishes contact with the server and should resolve your problem.