The issue is that you aren't sending the appropriate RegID value to the page. If you look at the working page it goes to something like:
But the non working page just goes to:
The recordset is set to filter based on the RegID passed in the URL and it won't work without it the way it is set up now. The key is making sure the Recordset on the page is filtered to the correct value by either passing in the RegID, or by doing the filter manually if each will have its own page.