Please help me.

My iGO (Android) keep silent when I use radio at same time. But the GPS has sound when I turn off radio.

Could you please tell me how solve this problem to let them work well together....

Thanks.

This is to do with the hardware you are using. But you didn't say what hardware it is, so I doubt anyone can help.

A guess...
If its an in dash unit, open the equalizer or volume control and raise the gps volume if you have it separately (like bloetooth volume, media volume...).