File Plugin : no preview with image file

Hello,

I have a problem with the File Plugin : when I upload an image file, I can't have a preview for it. I tried different one (png, jpg ...) with different size, but I got the same result.

I have the same problem when I upload an image for an icon group but I don't have this problem with the icon profile.

Does anyone have any solution for this problem ?

Thanks for you time