Expression based on Distinct value

[amber2000]

Hello everybody,

I have a problem to make an expression based on a Distinct value.

The expression I would like to make looks like this:

Field 'Gecontroleerde_Colli':

Sum ('PC_Colli_Checked' based on the Distinct value 'PC_Ass')

Nothing I do works, can anybody help me with this issue please????

I'll atach a copy of the QVW.

Monique