Use the AfterUpdate event procedure of the DateResolution check box on your
form to set the value of the yes/no field:
Private Sub DateResolution_AfterUpdate()
If Not IsNull(Me.DateResolution) Then
Me.IssueClosed = True
End If
End Sub
Before you do that, is the IssueClosed field really needed in your table?
Could there be times when an issue is closed, but the DateResolution field
would be validly null still? If the date in DateResolution was deleted,
should the issue be considered open again?
A better solution might be to drop the IssueClosed field from your table,
and create it in a query so it can never be wrong. Just type this expression
into the Field row in query design:
IssueClosed: ([DateResolution] Is Not Null)
You can use this query anywhere you would have used your table, and it's
always right.
More info about when and how to do this kind of thing:
Calculated fields
at:
http://allenbrowne.com/casu-14.html