I replaced two cordless phones with the updated ones as recommended by my vendor. They work but I cannot program the handset. If I disconnect the line (from the KSU) I can get to the programming menu on the handset but can't program (obviously because I'm not connected). But when I connect the line, I lose access to the programming menu on the handset. My vendor's tech support is stumped as am I. Anyone have any clues or things for me to check? Thanks

-Ken in MD-