A few thing to try.
1 If it is a home made cable from Digi box to TV check the cable and the ends are correct
2 check that the TV link shows a red light
3 (I think some TV links do not have a light) If it does and the light on TV link is off unplug Digi box for a few mins and plug back in.
4 Was the power to the RF outlet (RF 2) switched on. Go to services press 0 1 sellect this will take you to installer setup. Go to number 4 this will tell you what RF channel the Digi box is on also check that the RF outlet power supply is switch on.