Insert document in Authoring / Site at given position

Hi,

I want to insert a document into the sitetree at a given position. When I select
the entry which should become the preceding sibling, select File / New document
and choose "following sibling" in the field "Relation", the new document gets
placed at the last position instead. Am I missing something? My Lenya version is
2.04.

Thanks and regards
Markus Angst