Resizer preview picture is broken

Hello,

I have only one theme I bought on themeforest, and all was working well unitl I decide to crop some preview pictures on my posts.

My WP is hosted on a vps with nginx. But I already tried some hacks like activate the php gd module, and so on…

here is what I have on my picture resizer : https://img15.hostingpics.net/pics/448930Capturedu20150825122141.png

Here is something I didn’t get, because the json is send after the axaj call… https://img15.hostingpics.net/pics/604318Capturedu20150825122129.png

I hope you can help me to solve this issue…

Regards!