running sum in a query

[Kate]

Like many others, I am trying to do a running sum in a query.

This is my expression:

Expr1: DSum([Quality],"Master","[Instance] <= " & [Instance])

where instance is my unique identifier (just an autonumber created for
each record), Master is the name of hte table from which the query is
built, and Quality is a field containing the numbers I want to sum.
When I do this expresssion, this is what I get:

Quality Instance Answer
Answer if I remove the criteria
0 1 0
0
5 2 10
25
3 3 9
15
2 4 8
10
4 5 20
20

What am I doing wrong?

Thanks
Kate

 

[Kate]

That came out weird when I posted it...
Quality Instance Answer Answer if I remove criteria
0 1 0 0
5 2 10 25
3 3 9 15
2 4 8 10
4 5 20 20