Satellite Radio Help

I have an '08 F-250, with the stock AM/FM/6 Disk radio in it. I have the satellite radio antenna on top of my truck, as well as the sticker on my driver's side window that says I have satellite radio. And there's all the brochures in my owners manual and what not with all the satellite radio options. And, I even got a letter in the mail from Sirius telling me my pre-owned is equipped with it, and that I have free trial and what not. Anways, to the point; I can't access the satellit radio on my radio? My owner's manual says to press the Aux button to access the satellite. But, when I do, it only lets me access my "Line in" option, not the satellite. I guess my question is; does it seem like my factory radio was replaced with a non-satellite capapble radio? Or, is there a way that it may have been deactivated somehow? Or, if the satellite antenna cable was unplugged from the reciever would that make it not available? Long post, I know. But, just trying to get as much info out there as I can. Thanks all.

Andy.

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