Campaign "not deliverable" to Selection - Data missing

Hey There,

please excuse the upcoming wrong terminology, I'm using SuperOffice in German so I don't know the correct english terms...

I transferred the "Not deliverable" list, provided after an Email kampagne, to a selection, so I could see the responsible sales rep. of the addressees who couldn't be reached.

(hope this makes sense)

The "not deliverable" list in the campaign consists of 51 entries. The selection created out of that list contains only 34 entries (respectively 38, I tried it a couple of times and got different results).

This is kinda annoying as I can't detect whats the problem.

Tipps would be highly appreciated.