I want my macro to evaluate if a field in a SUBFORM is null, and if not, allow the user to click an option radio button. If the field IS null, then the user shouldn't be allowed to click. Sounds easy enough, right? I have this as a condition in my macro: [Forms]![frmupdatecaseentry]![SelectedStatusNumber]=6 And [Forms]![fromCaseFeatureSubform]![FeatureDateClosed] Is Null The problem is that I get an error message to the effect of "Can't find the subform 'fromCaseFeatureSubform'" - as though it doesn't recognize that the subform is open (the subform IS in fact open inside the frmupdatecaseentry main form). I've tried using the .form suffix after my subfrom name, but that doesn't seem to work. Any other ideas?