Checkbox filter - yes or all

[SueBK]

I'm trying to filter a query from a form using an unbound checkbox. The user needs the option to 'show all' or 'exclude superseded'. The superseded field is yes/no. I'd like to avoid the triple state because I don't think it's very user friendly.

I tried
IIf([forms]![frmDepartmentSearch]![Check1]=Yes,-1,"*")
IIf([forms]![frmDepartmentSearch]![Check1]=Yes,-1,-1 AND 0)

But neither work.

How do I specify "if checked" show only current; "if not checked" show all?

 

[SueBK]

Worked it out. Always the way; within minutes of posting.
IIf([forms]![frmDepartmentSearch]![Check1]=No,-1,Is Null Or -1)
OR not AND. DUH!

Now to remember how to get the query to refresh every time the box is checked or unchecked.