User Portal Application Server & DB 2.60B

Hallo, I have open a database 2.60B, wich was created under a client 2.60B, with the User Portal Client 2.60D, now when I try to open the database with a client 2.60B, I get the following error message: “Is not possible to access the database with the current version of Navision Financials. Take a backup of the database with the previous version of Navision Financials and restore it with this new one.” I have maked a full backup of the database, from the client 2.60D I have created a new empty database, in wich I have restored the backup, when I try to open the database with the client 2.60B the error messages is still there. Wath can I do to use my database with both the clients? Thanks in advance Lukas