How to find the correct segment based on the value of a field within it ?

Hi all,

I am struggling with my mapping.

On the source-part I have DEBMAS07 with multiple E1KNVVM-segments and also multiple E1KNB1M-segments.
For every E1KNVV-segment we create a target-structure. One of the fields within the target needs a value from the E1KNB1M-segment. To know which segment, we should compare the field VKORG (from the E1KNVVM-segment we are currently working on) with the field BUKRS in the E1KNB1M-segment.

Now I seems not to be able to select the right E1KNB1-segment.

Anyone who could advise me how to do this ?
Thanks in advance !

Greetz,
Kurt.