Verified answer

771A problem communicating with dish generally is a power problem, while 771B is an overloaded SWM (unless your in a MDU, you wont have to worry about that). Make sure to check power on your power inserter, or multiswitches if you have them. Also check all the fittings, connections, barrels, cable and splitter to make sure they are all DTV approved and rated for at least 2GHZ. If all else fails, call DTV and have a technician check it out.

I'm a member of this forum so I looked up what I could find and this thread pretty much sums it up:

http://www.highdefforum.com/directv-forum/74471-hd...