Help with calulation and sub form

[Wayne311]

I am in the process of updating a Paradox V4.5 application to Access 2010. 1992 was the last time I did this…yikes.
I have a form (Receipt) with a sub form that allows packages to be delivered to multiple areas (Districts) with one paid receipt. A linked source table has the district (number 1 to 6) with corresponding charges. I need to have a total cost calculated based on the districts in the sub form with values retrieved from [DISTRICTS]![CHARGE]. Any suggestions on expression, macro, etc.?
Thanks

[NoellaG]

Hi,

check out the DSum function.

greetings
NG