Hi Guys ,

i just brought a TMC-RDS for my TOmtom , for some reason i cant get it to work using the universal navcore , am i doing anything wrong ? ?

No clue as I don't know what you are doing.
But I do know that the receiver works fine for me on my Navcores.

ok so i find that sometiems if i do a hard recent and as its booting up ,i then plug thecable in . it automatically works . but it wont work if the device has come up from just sleep

That is a common problem, same for the problem of not getting reception unless the receiver is disconnected from power and plugged back into the TT.
I think it has something to do with the charging of the device, for some reason the TT not always recognises the receiver and in some cases the receiver fails to initialise so it can send the data to the TT.
Not all receiver models have that problem but if in doubt just start the TT, plug the receiver into the cigarette lighter and then into the TT - this way it should always work as expected.
You can also do some mods (suicide.dat) to frce the device into a fully off state instead of sleep, although pressing the reset does the same.