Then in your project’s domainmodel the association between TrainingEvent and Course is not many to one (*-1).
So go to your domainmodel and add/change to *-1, something like this:
Can you send us a photo of domain model appears the relations
hii Piyawadee Pengna ,, make you domain model like this and go to page and choose {before choose again select once none and ok to really change} entity for dataview again and click on automatically fill content yes button