BBC channels?

I am having trouble gaining BBC channels on digital.
I have an outdoor areial with a single cable coming into the house connected to a socket, connected to the socket i have a y-piece which feeds the tv in the kitchen and living room. The kitchen tv has a digi box and all channels are fine. The living room tv has freeveiw built in, I can get all anolouge channels but when i switch to digital i cannot receice BBC1, BBC2, BBC3, and ITV2 and C4+1 stutter, all other chnnels are fine, if i disconnect the y-piece and plug the cable into the socket all channels are fine, there is no difference if i just disconnect the kitchen tv. i have tried 3 y-pieces and stuck on what else to try.