Well, either you still have a wiring problem in the cable from the lounge TV to the kitchen, or a combination of poor aerial alignment & low sensitivity tuner, or simply the TV is on the analogue tuner and you live in an area where analogue has been switched off. If so, put it on to the Digital Tuner (DTV) and retune
Next, try the RF2 feed from Sky box to the kitchen. Check this first by tuning the RF input on the main lounge TV to the Sky box. (aerial lead from RF1 to lounge TV, TV on analogue - pick a vacant preset number, say 9, and tune to the RF output of the Sky box - probably Ch37 if it hasn't been altered. Then connect kitchen TV wire to RF2 - repeat process for kitchen TV.) If still no signal then the aerial wire going to the kitchen is knackered, or the TV tuner is knackered in the kitchen TV.