I've had mine for a few months, works great. Then now when I plug my iPhone it doesn't charge the phone anymore, also sometimes when I plug it, the music will play but sound is through my iPhone speaker and I'm able to control and change music on my OEM radio.

 

I had a similar charging problem with the USA-SPEC interface with my 1st gen nano. It didn't charge the day I bought it but everything else worked. I ended up exchanging it because I thought it was defective and the second one I got worked with no problems.