I am a student in applied computing course, we've just began learning access. I had a simple task that I think I've done it, except one error that keeps popping up every time I try to set up a PK for a particular table. Please tell me, what is wrong. I've tried to fix that, following the suggestions in the dialog box, but the error kept popping up. Please open file Capture3.JPG to see the error. Thank you!