Hi, i'm a new member. Have been trying to connect a 4/4 switchbox to my direct tv. i have a tuner/tivo all in one unit. the switchbox i have has four inputs of 13v and 18v and has 4 outputs. i connected the direct dich out to the input of the switchbox and then the output of 1 to my tuner/tivo unit, but got no picture?? what am i doing wrong?? also which of the two input connections should i use, the 13v or the 18 v??? thanks, manny