error 3326

[jaco123]

I created a query that pulls information from two forms. I then put that query on a form with a extra text boxes were you put a value in. When I press a button the following must happen. It must take the value from form 1 (payment) and it must multiply it by the text box value (rate) then it must add it to the value from form 2 (balance) my coding is as follows
Balance = balance + ( payment * rate)
As soon as I run the program I get error 3326. I even put it as dimensions then the code looks like this.
Dim a,b,c as integer
a = balance
b= payment
c = rate
a = a + ( b*c)
Balance = a
Every thing works but as soon as I hit the last part of code I get error 3326. I know it is something stupid and something I must know but I just can't get past this code. Please showe me were I make a mistake

[June7]

Can't do running aggregate calc like this in Access form. Requires nested subquery or domain aggregate function.

It is possible to do running calcs on report because textbox on report has a property for that.

[jaco123]

Hi June 7 I didn't mention that I do the coding in the visual basic function of access

[June7]

I assumed VBA. Still think won't work and comments apply.

But maybe need to know more about the data and query.

If you want to provide db, follow instructions at bottom of my post.

[John_G]

You are getting the error because the query is not updatable, meaning you can't make changes to the data in any of the fields. This often happens in queries which join multiple tables. They can sometimes be made updatable by putting indexes on all the fields used in the joins. Aggregate queries (using group by etc.) are not updatable.

You might not need a query though - if the forms are both at the appropriate records, could you not just reference the fields directly?

Just a note - the Dim a,b,c as integer does not define all three as integers - only c is integer. The other two are variant.
you have to use Dim a as integer, b as integer, c as integer