Cannot Add Database Diagram in SQL Server 2005

A few days ago, I needed to create a database diagram out of a few tables in the database, and I was surprised when I was not able to. Everytime I clicked on the ‘Database Diagrams’ subfolder of the database in the database tree, I was met with the following error message:

The error message says that “Database diagram support objects cannot be installed because this database does not have a valid owner”. It then proceeds to ask you to alter authorization of the database owner to a valid owner using the Files page of the Database Properties.

Following the steps in the error message doesn’t seem to get around the problem, or at least in my case it did not. I tried changing the owner to another login, and that just did not do it.

Then I noticed something,  on the ‘Options’ page, the ‘Compatibility Level’ was set to ‘SQL Server 2000′ rather than ‘SQL Server 2005′.

Changing it to the right version of SQL Server seems to eliminate the problem. So if you come across this problem and you’ve tried giving the appropriate authorizations, go ahead and change the ‘Compatibility Level’. Once this is done, try expanding the ‘Database Diagrams’ node and it will ask you to install some support objects. Go ahead and accept it. You should now be able to create database diagrams.