Validation Network header CJ20N

Hi experts

I am trying to make a validation on network header in trans OPSI. I want an user exit in which I can make some validation in trans CJ20N when saving. I would like to validate the profit center on the WBS element and on the project, because if you only make a change on the network header you can save without validation af the project and the WBS element is done. I would like to make a validation of the profit center on both the project and the WBS element.

I have made the user exit but the data available in the user exit are not the data that belong to the network header (structure CAUFVD), but data belonging to an activity (structure AFVGD). Does anyone know why?

Thanks in advance

Kind regards Joergen, KMD, DK