[Plugin: Magn WP Drag and Drop Upload] Not working

WordPress 3.2
Plugin 1.1.4
Firefox 9

I try to drop the files to the especific space, the loader completes and I get the following error message “There was an error uploading this file”.
Someone have the same problem?

http://wordpress.org/extend/plugins/magn-html5-drag-and-drop-media-uploader/