Populating error with a "combined view"

Populating error with a "combined view"

I am designing an application "trading master", to track trading projects in the company. I have a problem with the view "Po item listing". I want to choose some of the date fields in the form "Purchase orders - PC", like "final inspection date", "vessel date", etc. But once I choose any date field, the populating process will fail.

Could you please look into it?
jianqiao