Hi Jim,
You wrote: "The question is why didn't the value change?"
This got me to thinking. To make a long story short, I found out that the listbox works fine unless it's on a page of a pageframe. In fact, if I put the listbox on a form that has a pageframe, but I put it on the form, not on the pageframe, it works fine. So there's something in my pageframe mechanism that's gumming up the works.
I experimented and found some additional info: the pageframe opens on page 2. The listbox is on page 1. If I go from page 2 to page 3 to page1, the listbox works fine. Buf if I go from page 2 directly to page1, the listbox does not work!! I am trying to figure out what happens when I go from page2 -> page3 -> page1 that somehow enables the listbox.
I tried the micro approach (I turned on coverage during the transitions and compared every line) but no results.
Then I tried the macro approach: I ran two instances of VFP. In one, I did the 2->3->1 maneuver and in the other id did only the 2->1 manuever. Then I used SYS(3270) (as per your FoxTalk article) and compared the values of the two listboxes. They were identical except stuff that just confirmed what I was seeing.
Now I am really beginning to feel stuck.
Do you have any ideas?

Thanks, Chaim