I want to connect my Sony dvd and HD pvr to my Toshiba HDTV with one Component video cable. I purchased a Phillips HD Switcher and connected component and audio to each input and an output component to the tv. I select the tv and everything works great. When I switch to DVD I get sound and no picture. I tried S video, composit, and component all with no success. When I connect dvd direct to tv it works. I thought maybe it was the box so I went to Radio Sack and purchased a 2 way component video selector. No change I have tried two different DVD plays and the problem exists with both. What can I do to make it work. The clerks in the store say to just plug the units in.