My code and the error result:
If DCount("*", "qryMsgBoxCriteria", "Item=" & Me!Item & "And IsNull(Actual_Pickup_Date)") Then
MsgBox "There is an active Reservation on this item, check for potential Date conflicts."
End If
Added Note: I think I actually see the problem. It's not the code -- at least I don't think it is. I may be wrong on this. While my subform is displaying the records just fine, it also has a new record started with just the Item field populated, so I wonder if it is affecting the query. Gotta figure out how to not have the subform default like that.