Something is wrong with my Aux input

Alright, I just got Sirius Radio for Christmas a couple of days ago. This morning I went ahead and installed it. For some reason, when i switch to AUX IN mode, it only plays out of half of my truck. here's my info, so you know what i'm working with:

Truck: 2001 Ford Ranger, Extended Cab

Audio Equipment: HU- Eclipse CD8443, Sirius Sportster Replay

I've went ahead and used the Line out on the back of my sat. reciever dock, and ran the wire to connect it to the AUX in wire on the back of my headunit. with that, i also ran my power and antenna.. everything is working fine, but for some reason, it will only play out of the Left Channel. When i have my Headunit playing CD's or Radio, everything works great (and every speaker is working).

I took my headunit back out, thinking there may be 2 seperate AUX IN lines (one for left channel, one for right channel), but there is just one main one.

Does anyone have any idea what may be going on?? If so, please respond to this post, or email me at Strider0O0@aol.com. i'll be checking here on the boards for any update, as well as my email. thank's for your time guys!

I just tried another line, but had no luck. it's still playin on only one side.

thanks guys!

i didn't even know there was a difference! that sounds like it must be it. the sound is only coming from the Left channel, so that sounds like it's going to be it!

thanks again!