Calculating Amount which are 30 days overdue

[#1]

I'm trying to make the sum of amounts openstanding (AR) which are more than 30 days overdue.

I have the following formula , where Vervaldag = Due Date and BedragOpenstaand=Openstanding Amount

=Sum({<FactTypeId={5}, ">=$((date(today())-Vervaldag)>30) >}[_BedragOpenstaand])

Can any help.

Thx.

[sunny_talwar]

May be this

=Sum({<FactTypeId={5}, Vervaldag = {"=Date - Vervaldag > 30"} >} [_BedragOpenstaand])