After replacing my old DSS receiver with an RCA DTC-100, I decided to hook the old one up again. The old one is an RCA DRD515. But when I hook it up, I don't get any satelite signal at all. I thought that the DTC-100 would still be on the old Sat. Do I have to get on the roof and tune in the newly installed receiver? If so, how will it affect the DTC-100? It took a while to dial it in and I don't want to screw it up.