dlookup

hi



I have 2 tables

1. order details

2 invoicedetails



in the table "order details" I have a field called , productno and required( required in a date field)



in the table "invoicedetails" I have a field called procduct no1



what I would like to do is get the result "required" in my dlookup of the "required" date where the productno and product no1 match numbers match



I did try this as I am just learning dlookup but it failed.



requireddate: IIf(DLookUp("[productno]","order details","product no1= '" & [invoicedetails] & "'"),[required])







any help appricaited

dlookup