Dlook up Access
 

I have created a form with a field name (Store). How can I create a flag that
when a store number is entered in this field it will automatically check in
another table to verify if the store is open or closed.

The other table contain two fields Store and Date.

I tried Dlookup
=DLookUp("[Date]","[Closed]","[Store] = Forms![Closed Store_FRM]![Store]")

I tried IF statement
= IIf ( [Store] = Forms![Closed Store_FRM]![Store] ,Stop!, Go!)

Had no success