Error loading XML Theme with Thememanager

[Georg Draxler]

Hello

i am using a ribbonbar in my visual studio 2008 project. I also use a RadThemeManager. 

i tried to load a xml theme from file. after selecting the file an error is coming up:

Error loading theme from resources System.NullReferenceException...

look for the error at following screenshot:

http://twitpic.com/j3u12

What i am doing wrong?