Have you checked the quality of the cables. They usually have what type they are written on them. If your using anything other than solid copper center conductor then the high freq. Copper Clad Steel cable is used a lot by contractors and its usually is what is installed inside a home, hd signals won't pass as easily. If cheap wall plates or barrel connectors are used that can also cause a glitche in passing those higher frequencies. Connectors which were improperly set will cause problems like that too...