If you are receiving an "Invalid Exclusive Content Key" error, please try the following:
Start by making sure you are entering the key in the correct location.
1. Select Extras from the main menu
2. Select Additional Content
3. Press Y for Redeem Code
4. Select Ubisoft Code
Next, please enter the key exactly as listed with capital letters and the dashes.
If still unsuccessful, please contact ubisoft support: http://www.ubi.com/us/support/ and submit a digital image of both the key card and dated receipt along with the FULL error message for further assistance.