How to fix the error with FormGridControl?

I got this error, but I have already added all the necessary fields and datasources to them. I have no idea why it says that GridControl is empty.

Severity Code Description Project File Line Suppression State Error Path: [AxForm/JournProductUpdate/Design/Controls/MainTab/HeaderTableFields/FormGridControl1/DefaultAction]:Property 'DefaultAction' on control AxForm/JournProductUpdate/Design/Controls/MainTab/HeaderTableFields/FormGridControl1 cannot be empty per pattern 'Details Transaction'.