Worpdress doesn't resize uploaded images

Hi everyone,

I’m having a problem with the images which I want to upload. The upload goes well, but WordPress doesn’t make the resizes (thumbail, medium, large) but uploads only the original. I’ve setted the formats in the CMS settings.

When I’m checking the files on the server they aren’t created. WordPress used to create a couple of files, for example when I’m uploading “image.jpg” it will create: “image-200×200.jpg”, “image-400×400.jpg” and “image-960×960.jpg”. But it doesn’t work anymore for some kind of reason.

I’m using WordPress 4.1 on a Linux server with Apache 2.0 Handler and PHP version 5.3.29. And the CHMOD permissions are exactly the same (644) as the files which are created before and WordPress did resize that images!

Can somebody help me through this problem? Thanks in advance!