Header Picture doesn't show up

Hello everyone,

I’m getting desperate with the Brunelleschi Theme, because I tried to upload a header and the picture won’t show up. This Theme offers the possibility to display a custom picture, but why is it not working?

http://www.project-beautiful.de/wordpress – here you can see the issue. There is just my Blogname, but no picture

I have to give the tiny information that for another theme I changed something in the header, but is this related then to all themes?

Well I hope someone can help me

Kind regards
Alenija