Trying to use multi switch - DirecTV DVR

For Trying to use multi switch, relating to DirecTV DVRs and receivers. i got three lines comming from outside. Two from my triple line LNB and one comming from my high def off-air antena. I ran all three through a channel master multiswitch. then with only two lines running to living room i used a radio shack diplexor to break out the signal into sat #1, sat #2 , and antena inputs. First let me say that signal works great without using the diplexor (but i want to take advantage of both sat inputs and off air antana), but when i use diplexor the DVR cant get a signal form one of the two sat inputs. I even tried to use a simple sat line splitter to take advantage of both sat inputs and no matter how I try to split the sat feed the receiver only sees i sat. When i go to test the signal strength it reads 99+% on both sat lines. Whats up? Help anyone!