Unable to sum calculated column in a subform

[Guest]

Hi,
I have a subform which contains the following cols of data in the Detail
section of the subform.
Name Amount Total_Amount

where the Total_Amount is a computed field which cotains
"Forms!Mainform!Ratio*[Amount] where Ratio is a field value from the
Mainform.
For example:
Name Amount Total_Amount
Myname $1.20 $2.40 (i.e. $1.20 * 2 (Ratio=2))

In footer section, I am able to use "sum(Amount)" to add up the total of
the Amount column. However, when I tried to "sum(Total_Amount)" column, it
returns #Error as output instead of result.

Can someone please help ?

 

[Duane Hookom]

You can't sum controls. Use:
=Forms!Mainform!Ratio*Sum([Amount] )