Validation in product cockpit

Hi everybody,

I have a question about product cockpit, as of now, I used validator to intercept a approval status change in product cockpit, it will show a validation message in the Editor Area if fail to meet some requirements.

The message will show when user change the value of approval status using the following method

but it won't show the validation message if user uses to change the approval status.

Both method will result in no change in approval status, which is expected, just I am not sure how to make the validation message shown in both methods.