gianmarizzi on "[Plugin: WP Smush.it] Smush.it generates error when uploading pictures"

Hi,
I'm using this plugin with Enfold theme (www.kriesi.at) but whenever I try to upload an image (no matter its size) I got an error message. I dismiss it, go to media library and find my image there. Go back to my page and insert the image from library.
If I deactivate Smush.it, uploading works fine.
Check compatibility is 100%.
I also have All In One WP Security.

http://wordpress.org/plugins/wp-smushit/