Spec dock charging problem with iPhone

I just got a new spec dock to mate up to my dice mediabridge that I just installed in my 2002 M3 cab. Unfortunately, I'm having a challenge getting my phone to charge, which was a big reason for getting it.

The install was fairly straightforward, and I can currently play music through my mediabridge on the USB connection. However, I cannot seem to get my iPhone 4 to charge while in the spec dock. Plugging the iPhone into the USB port directly (bypassing the spec dock) with an apple cable results in the phone charging properly, so it doesn't seem to be a problem with those two. I also am getting no errors when I plug in the phone to the dock either.

Has anyone else had a problem with their spec dock? One thing I've noticed vs any other pictures of the cable end of the spec dock on mine ends in. 30 pin female connector, vs a round pin like I have seen in many videos online. Is it possible the combination of the two (white 30 pin able cable to USB plus the cable on the spec dock) is causing too much voltage drop?

I also saw on spec docs website they sell a charging pigtail that appears to go between the dock and the output device it connects to. Not sure if maybe indeed that instead?

Thanks!