Modx Easy 2 Galley doesn't create images in thumbnail

It looks strange, but when I synchronize my g开发者_开发技巧allery all little images from folder '_thumbnails' are deleted and not created again. But big images exist in folder 'gallery'.

chmod 0777 gallery/_thumbnail - didn't help

My version of Modx is evolution.

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Have you checked ownership? I've had problems with the same thing in the past. Make sure the ownership of the gallery/ (recursive) is apache or higher.