Thanks! Thanks for all your help! I called Dish and we do have legacy LNB's. So I'm going to get a SW-64 switch and that should solve the problem. Thanks again!

I am upgrading from two basic receivers to one basic and a 721 PVR. We have a Dish 500 with dual LNB's so I need to add a third line. I bought a SW34 switch on E-bay and connected it but can't get the three lines to work. I've tried several combinations of the 3 input and 4 output connections...