How validate fields in a plain window

OK in just a window procedure, So how do you validate and reenter stuff?
I have a window I User enteres into 2 fields I want to make sure all ok before proceding. Normally I’d do that in TakeCompleted, but in just a window thats never entered. So I put it in ?OK takecompleted, but it never goes back and just exits

I have an entry field with lookup information and also an accompanying FieldLookupControl Button.
The Entry field has skip and readonly flags (To basically force a lookup). I was selecting That.
I changed to select the button and all is good.

Before TakeCompleted of ?Ok button, you may use CYCLE to return the screen again. Also try to use SELECT(?SomeField) to navigate correct field.