H John,
There is one issue you can check on your end to resolve this, the other issues need help from the support team. In the first instance, please make sure the account you are applying the invitation code to has the same email address associated with it, as the email address the invitation was sent to. (i.e. If the invitation was sent to x@yourdomain.com, and your account in adCenter is set to send emails to y@thatdomain.com, the invitation won't work.)
For all other issue, hover over the yellow triangle and note the error message it gives. Should be something like "Invitation code invalid". Please contact support at the following link with the error from that page for more help with that issue:
https://support.adcenter.msn.com/eform.aspx?productKey=gatineau&ct=eformts
Thanks,
Brian
