If you are defining a validation or substitution and the field that you want to use in the validation/substitution does not exist (even though you know that it exists in the relevant table, e.g. BKPF) you need to do the following:
- Go to transaction SM30 and enter table VWTYGB01
- Search for the relevant Table and Field and deactivate the “Exclude” checkbox, and save the settings
- Run program RGUGBR00