I have 4 directv receivers. One is HDTV. I was missing transponder 8 SAT C signal(HDTV channels) on the HDTV receiver. All the other TIVO receivers showed good signal strength on all transponder on SAT A,B and C. I replaced the HDTV receiver which did not fix the problem. I changed the multiswitch and now I have a worse problem. One TIVO receiver gets good signals on all satellites, but the other 3 are missing transponder 1-25 on SAT A and transponder 26 on SAT B. the signal is OK on SAT C. Why would one receiver get good signals and the other have missing transponder signals?