Thanks, but I'm still seeing the same problem. I did have mine in an option box, but with no default value set. However, when entering a new record, it automatically went to "No" on the form. Try it and see.
I noticed on yours, you set the default value to -1 (yes). Is there a way to do it so that it doesn't have a default value AND it doesn't check on anything until you want it? In my database, I don't want a yes or no until it is physically checked on. Otherwise it should stay blank.
Either way, I noticed it doesn't update in the table itself. The form will automatically check on No, but the table check box stays blank -- ??