Picture broken when "size" is given

Hi,
I have a strange behavior in my xwiki: When I add an image on a page, everythings work fine.
When I resize the image and go to preview or safe, the image is broken.

The page is empty, but just the image:
[[image:Kanu.JPG||height=“221” width=“525”]]

Does anybody have an idea? It’s seems to be on all pages.

Additional info: Export of pages as PDF works…as long as there is no image on the page. If there is an image, I get a Java exception

This one fixed itself be a server restart. I thought I already did that.