>>Interesting, why do we need to set this variable to SUM and why it didn't work in OnEntry of the Group?
>>
>>Anyway, I'll try that now, thanks a lot.
>
>If you don't set the calculate option to SUM, it will try to reevaluate the expression for every detail record that is processed. When it does that, it will wipe out the value you put there. So .. to get around that .. you give it an expression of zero, and tell it to SUM, which is what it does for every detail record but adding 0 to what you already stuffed into the variable doesn't affect the outcome.

Thanks a lot for the explanation.