Deleted all records from a table, can't add new ones. How come?

[ResearchRN]

I created a simple database with a single table and a form so I can track patients enrolled in a study. I added a few test records to make sure everything was working properly. Now I'm ready to use the database for real. Only trouble is, when I erased the test records I find that I can't add new ones. Can anyone tell me why and what to do about it?



Thanks.

[June7]

Provide the db for analysis. Follow instructions at bottom of my post.