iMessage says, check your network connection? :L

Why every time I try to sign into iMessage with my apple ID, does it continually ask me to check my network connection? I know my ID is correct, I know my internet is working and my FaceTime, ping chat and skype are working... i dont understand...

I have done the clasic "turn off then on again"

I have done restored it TWICE

and I have made a new apple ID

the men in the apple store told me to restore it but that didnt work nor did it when i connected to there wifi instore..

HELP?