SVN 639 - error while making a normal folder to a parent

[Florianer]

Hi,
next I tried: I have (an empty folder - security first ^^). Now I tried to rename it into a parent folder. I mean, I have created

...
...
test
...

Trying to create a folder named test/sub (<- / because I am on All-Inkl server, separation is / and not . ) results in an error.
Creating parent/ shows up these:

...
...
parent
test
...

Trying to create parent/sub ends up with
...
...
parent
parent/sub <- where sub is the subfolder only visible as a nested folder on email view
test
...

Trying to rename test to test/ results in an error.
Is it possible to fix that in that way, that I can make a normal folder accepting subfolders by 'renaming' and _without_ loosing emails inside?