ValueListItems( ) returning nothing via a working relationship & related value list

I suspect I’m forgetting something simple. I have a relationship and I’m successfully showing the correct related records in a portal.

On that same layout from the context of that main table (not a TO of it), a calculation is failing with    ValueListItems ( Get(FileName); “valuelist_name”)  It’s coming up blank. The value list however, is working. It is being evaluated from the context of the main table. When I put a field on that layout and assign the value list to a drop down field, I see the values. How on earth would this ValueListItems function be failing. 

Other calcs in this solution (albeit in a different table) with ValueListItems ( Get(FileName); “valuelist_name”) are working so it’s not a problem with Get(filename) or the file as far as I can tell. The selected field in the related value list is indexed, and the calc trying to use ValuelistItems ()  is unstored.   Any thoughts about what I might be doing wrong?

The relationship is a self-join to a TO of the same table, from a stored calc in the main table resulting in a text field (the word "yes"), to another text field in the TO which is an indexed text field in which some records contain the word "yes."  Like I said the drop down list is working.. Any idea why ValueListItems( ) is not

Many thanks in advance.