Thank you. Yes, you are right about the reference, when I use the expression builder it shortens it to just [SCHOOLID] etc.
I tried your suggestion of: =DCount("*","KitloanCountQry","[SchoolID] = " & [Forms]![MakeaKitloanBooking]![MembershipSubform].[Form]![SCHOOLID] & " And [DateOut] > #" &...