First, disconnect power from receiver for several minutes. If all is secure, trace the line going into the house. If there are splices or extenders or any taped areas anywhere on the coax line, make sure they are free from corrosion. Next, check the coax ends. If receiver menu and program guide look normal, the receiver is most likely working correctly.
Substitution is the quickest and easiest way to find the problem.
If you have a dual lnbf, reverse the cables. If you switched the problem to other receiver replace as necessary. If the card was used in another name, they will not authorize it. Multiple receiver usage requires that all receivers be connected to a phone line or they will lose programming. Make sure this is accomplished during installation.