New Post: changing from 1 SQL DB to another SQL DB holding a copy

Try to restart the website (edit web.config for example) to check if there's another exeption occuring before this one.
Alternatively, using a newer version (4.3) should give you a proper exception text.

It still must be related either to connection string, possible configuration error or sql user's permissions (you can try to log in with Sql Server Management Studio and check if you see the tables).