that sounds like a billing code error on your dtv account, or the access card hasn't gotten an authorization "hit" from the sat. the age of the equipment might have caused an equipment setup error on your account, you need an experienced tech rep (preferably from their denver call center).
call dtv tech support back while the box is hooked up to the sat, insist on a supervisor, and best of luck - they really don't want you keeping this box in circulation.
The truth will set you free. But not until it is finished with you. - David Foster Wallace