Hi, Raymond -
I can understand how frustrating this situation is for you.
If I were in your shoes, I would get "out of the box creative" to see if I could perform the same or similar GetChild and get return code of 1...from anywhere in the window - here are some ideas:
1. Declare another DataWindowChild reference variable and try the GetChild using the new variable.
2. If the failing DataWindowChild reference variable is an instance variable, see if a locally-scoped variable works.
3. Try issuing the GetChild from other scripts in the same window. Maybe even temporarily adding a "Click Me!" command button to the window and test the GetChild in the Clicked event.
4. Code a new GetChild call in a window function, then call that function from the spot where the failing GetChild is being called from now. Call it normally (Trigger), try it by Posting the function call.
5. Verify the requested column name exists in the DW, not only by inspection, but try issuing a Describe function that references a property of that column object, then check the result.
I'm sure that are other things you can try...these are what I thought of while typing.
Hopefully you will discover one or more ways to successfully invoke the GetChild function. If that doesn't give you any clues why the original GetChild is failing, report your findings back here (specifically, what you tried, what worked, what didn't work) and we'll bonk our collective heads around some more.
Good luck!
John
Regards ... Chris