Forms :: Adjusting Query In Form

I'm trying to perform a task that I'm absolutely certain is simple to do.. if you know how to do it. I'm trying to add three check boxes in the form header to affect the query related to the form.Each is a simple Boolean, and simply want to apply a "WHERE col1 = val1, col2 = val2, col3 = val3". Like I said, very simple.

It seemed like I could just use a Macro in the click event of the check boxes, and use a SetFilter within the macro that applies a Where Condition = [Shipped] = [chkShipped].

This... almost works. When I click the checkbox it asks for the value (it doesn't know how to process [chkShipped], which is the name of the corresponding checkbox). So that's broken, but if I provide 0 or -1, then I get the expected result.I would like a 3-state checkbox, but I can't even get this working. I can tell I'm either close, or in the entirely wrong direction.