Upgrade to latest Maxsurf (22) - licensing

Hi

I have just downloaded the latest Maxsurf (22.03.00.121).  I have been running on V21.14 until now.

When I try to open the V22 product I get the message "User does not have a valid entitlement to use this product".  I assumed I would just be able to run the latest version with my current license?  What are the restrictions?  I have the CSS subscription.

Any help would be appreciated.

Andrew