Set analysis sum value between 2 values doesn't work

[Michiel_QV_Fan]

I created this expression:

sum({1<[CE.cijfer_thesis] = {">$(=avg([CE.cijfer_thesis])-Stdev([CE.cijfer_thesis]))<$(=avg([CE.cijfer_thesis])+Stdev([CE.cijfer_thesis]))">} [CE.cijfer])

which gives this result:

and that is correct but the result of the sum does not show anything (a '-')

What am I missing here?

[MarcoWedel · Accepted solution]

please don't create multiple threads for the same question:

Set analysis sum value between 2 values doesn't work

thanks

regards

Marco

[Michiel_QV_Fan]

my browser froze, apparantly the post was done therefore a duplicate..