Bioware Social Network and linking you Xbox Gamertag

I try to link my Xbox Gamertag and i cant. i have linked my gamertag in Battlefield Bad Company 2 and Battlefield 3, but i cant link in Mass Effect 3 because i want to sign in on that account like on my Bioware Social Network. I have spent hours trying to link my Gamertag to Origin and EA. Can you help me on this?