Problems connecting OEM Sirius in 2006 X3

[sna77]

So I attempted to hookup my Sirius unit today and ran into problems. I've hooked up multiple Sirius units in my e46s and never had an issue.. This was my first attempt in an X3..

I followed the instructions here that came with the Sirius install kit I purchased from the dealer.
http://www.bigpatsfans.com/E83SiriuswithoutNav.pdf

The Sirius install is fairly straightforward. If you don't have a CD changer (where is it located anyhow?) there are 3 basic connections:

- antenna (I put the correct end onto the antenna)
- ibus connection
- audio connection.

Hooking them up takes about 30 seconds--you simply connect the 3 cables and that's all... They can't even connect the incorrect way--there is only one way to snap them in.

Anyhow, I connected the unit, and hit MODE on the radio until I get to the SIRIUS input. There is signal (I can change channels, and don't get the "acquiring" message) but there is a popping sound coming from the radio, and no music can be heard via the Sirius input.

I know this Sirius unit is good, as I just pulled it from my wife's e46, but I decided to try another one just to be safe--same results. I also connected another Sirius antenna (as opposed to BMW sharkfin) and had the same results.

Anyone have any ideas?