Well, at least AT&T is consistent in how they screw this up. They added to your account one additional receiver you did not ask for. They added 9 to mine. So, hey, you're winning ! All kidding aside, keep at it. The tech should know what to do, they call the "TEC Modifications" dept. everyday to activate new installations. He just needs to get your 4k "turned on" by them, the only ones who can do it. BTW can I suggest you slightly change the title of this thread to "Channel 104- Error Code 721" ? I think it might help others going through the same thing and can't tell from the thread's title.