sum on a subform problem

[Stuart Green]

I have a continuous subform which has 2 fields on it bound to a table . These fields are [volume] and [rate] where rate is a percentage. I have a third calculated field (unbound) on the subform that mutliplies the volume by rate to give me an amount due. I have called this unbound field [due].

What I want to do is show some totals in the subform footer.
I can get the volume field to add up by using =sum([volume]).
When I try however to show the sum of the calculated field in the continuous subform footer using =sum([due]) I get an #error (it also then errors the volume sum which previously worked OK).

Because [rate] is a percentage I can't sum this then do the calculation on the footer

Any ideas how to get around this please

 

[Rich]

=Sum([Volume]*[Rate])

 

[Stuart Green]

Don't you just love this forum! Thanks Rich, once again you've saved the day