Adding Custom Fields to FAGLFLEXP Table

Hello,

We have a requirement to update WBS Element for Planning related Data. So have added custom field(WBS Element) in structure CI_FAGLFLEX04.

The field is visible when I open FAGLFLEXP table, but when I post data The custom field (WBS Element) is not being updated. Could you please let me know the process to update this field?

Thank you in advance.