[Plugin: Slideshow Gallery] Visual editor button not working in multi site

Since I like this plugin, I’ve also tried it in a multi site installation. Although the slideshow and the shortcodes seem to work normally, the visual editor button doesn’t. When clicking it opens the popup menu, but it only shows the grey title bar and an empty white area.

http://ww.wp.xz.cn/extend/plugins/slideshow-gallery/