Frd04-aux only plays through left speakers

I installed the Pie Frd04-aux to play my ipod through the radio in my '06. It works great but it only plays through the left speakers, it plays on the right but it is so faint you can barely hear it. I tried switching the RF cables that go into the box but it still only played through the left side. Any ideas?

Apparently cause I didn't change anything. Wonder if my box is defective