2LIS_11_VAITM: Fields in VBAP missing in LBWE

Hi,

I want to add a field to my datasource 2LIS_11_VAITM. The field is available in an append to table VBAP. Unfortunately the field does not show up in transaction LBWE in the list of fields that can be added.

How can i get this field in the LBWE-list?

Thanks!