KEDR - Derivation from PSPNR

Hello

We have some settlements from PS to CO (PA) module. From the WBS number (PSPNR) I would like to derivate a characteristic (VKBUR), but unfortunately I don't succeed making a range of PSPNR as source fileds. The error message is: "No "from" or "to" values can be entered for this source field".

Does anybody have an idea how to solve this?

It isn't optimal to maintain each PSPNR in a project in KEDR...

BR

Søren