Variable Text - Last used

[Mark5CC0]

I'm working on a book that has part numbers embedded throughout it. Each page has a running head that needs to include that last used part number. I need a text variable that will pull the last used part number. However, when I use "first on page," it's pulling a part number listed later on the page. Is there something I could do?

[SJRiegel]

Why are you using First on Page when you want Last on Page? Or am I completely misunderstanding your process?

A few screen shots mocking up expected result and actual result, as well as the dialog box, would be helpful in figuring out what is going wrong.