Boba is probably right, it probably is a software issue. The download will enable the receiver to look for and recognize the 129 orbital location. The software in the receiver determines what it will look for and recognize.
First, check the cable from the dish to the receiver. Having the wrong type of splice (or a splitter) can also cause a satellite to "drop off." Splices should be done with an F81 type splice rated at 3Ghz.
Is this a new, unactivated box? If so, go ahead and do the check switch and confirm the 119 & 110. After you do this, select "done" (I think) and if it is a new, unactivated box, it will tell you it needs to do the download. Tell it yes, and let it do its thing. After it gets through, run another check switch and the 129 should be there. If everything is ok on all 3 orbital locations, then you're ready to activate.
If it is a previously activated receiver -
Menu - preferences - updates - (I think....can't recall the 211 menu from memory) and then use the big red button on the remote to power the receiver off and then leave it. AFter a little while, it should do the update.