The USB connection to your phone is completely unrelated to the RC connecting to AC. One can function perfectly normally without the other. There are only 3 possible reasons your phone is not connecting:
1. The USB cable is a charge only cable which doesnt allow data communications.
2. The settings for the USB port on your phone are incorrect.
3. The USB board on the RC is bad.
If you have tried different cables and phones then its likely number 3.