Custom fields in MDG-M getting cleared

Hi All,

We have extended standard SAP MDG-M with custom reuse entity by following document

http://scn.sap.com/docs/DOC-27859

We are able to get custom fields on newly created UIBB but they are getting cleared after any action performed on screen for ex. SAVE, CHECK, SUBMIT etc.

Please suggest how data from these custom fields can be updated to custom Z-table.

Regards

Pankaj