Xbox live 48 hour trial card probelm

I have a problem with the 48 hour trial card which came with my halo 3. The problem is that it is only a 11 digit code :? , eg. XX-XXXXXXXXX . But when i try to use it the code space is 25 digits or something. Does anyone know how to use this 11 digit code for the 48 hour trial?

Please help!

Chances are you are looking at the wrong code. All codes for 360, whether they are 48 hour trials, subscriptions, free games, DLC or MS points are all 25 digit codes broken up into 5 blocks of 5.

Usually they are hidden behind a silver panel on the card that you have to scratch off