[BUG?] Some of my Apps Cannot be linked FV-75

I'm trying to "Link App" with a new document to one of my app store apps - i have 6 different apps in the app store, but only one is showing up in the list. Any idea what the criteria are to show things here? All of my apps should be universal, are either in Ready for Distribution or Prepare for Submission. I can't really fathom why the one that is showing is, and its not the one I actually want to use your app with so i'm kinda stuck. Thanks!