First I've heard of that.
What phone? What USB cable?
If using the included short cable, be sure it is all the way into your phone's USB connector. It's easy to think it is all the way in but not be. Also be sure you don't have a USB connected to both ports at the same time. I mean not plugged in at all in the unused one. Even if the other end of the cable is not connected, it won't work.
If short cable doesn't seem to work, try the USB A port at least for testing.