Howcome it won't let me play online?

I just created a free 1 month trial of x-box live, after going through all the details, I tried to play online on the game Halo 3.


But as I entered matchmaking, it would not let me play, It kept telling me that I need to be signed onto an X-Box live account in order to play, even though I already was. Is there something I did not do right in the account creation? is there anything else I need to do in order to play?

Howcome it won't let me play online?
make sure the profile you are using is the one you created for xbox live. sign out, then click on your profiles, then click the one that says live next to it.
Reply:you probably setup the account but didn't sign in...