I assume you're selecting the tables in the Database Expert, correct?  If so, you link from one table to the next on the linking tab of the expert - you don't have to create selection criteria for this.

What are you trying to do in your record selection?  Joins don't happen in the record selection formula - they're automatically created when you link the tables together in the Database Expert.  Without more details about how you're trying to filter your data after it's joined, I can't give you an example.