I bought this from Monoprice: "USB 2.0 A Male to Micro 5pin Male 28/28AWG Cable - 3ft" hoping to charge the phone away from home by plugging it into a computer. But all I get is an option to mount the SD card as a drive to copy files. It doesn't seem to be able to charge the phone. Do I need a special cable, or maybe a second charger from T-Mobile? I had always charged my old MP3 player with USB, so I figured the phone could do the same thing.