Unable to delete uploaded theme

i tried to create a custom Theme
(downloaded from https://jazz.net/wiki/bin/view/Main/WebUITheming renamed to "custom1.zip" and uploaded it to the web client.)

ok, so that doesn't work,
there were no changes to see.

Then i created another, more simply theme, "custom2.zip" and uploaded it.
Again, clicking at "preview" seems to have no effect.


BUT, if i just "accept" the new theme, its there :)

so i wanted to delete the themes by clicking "delete" and get the following error in my chrome console:
"DELETE https://<server>:<port>/ccm/_theming/custom1 500 (Internal Server Error)
A::17
Error
arguments: undefined
message: "Unable to load /ccm/web/dojo/../../_theming/custom1 status:500"
responseText: "Interner Serverfehler"
stack: ""
status: 500
type: undefined
__proto__: ErrorPrototype" :?


in firefox 3.6.20 the error is like
"<server> : server does not support RFC 5746, see CVE-2009-3555"
"Fehler: Syntax-Fehler
Quelldatei: https://<server>:<port>/ccm/_theming/custom1
Zeile: 1, Spalte: 1
Quelltext:
Interner Serverfehler"

IE8 just says:
" Error: Unable to load /ccm/web/dojo/../../_theming/custom1 status:500"


What do i am doing wrong?
Is this a bug or did i just miss something?
How can i get rid of these custom testing themes?


I am using RTC 3.0 iFix 1 (RJF-I20110307-1521),
with an DB2 database