Car Dock - music not playing via audio out

[jlewis]

I just tried my Photon in the car dock for the first time. When I tried playing music, it only played through the phone's internal speaker. I have an aux audio cable and if I plug that into the headphone jack without the dock, the audio comes through the car stereo. I plugged that audio cable into the audio jack on the car dock's usb cable but nothing came through it.

Any suggestions?