Nextgen thumbnail problem

Hi everybody,

I posted this 2 weeks ago and nobody could help me, I tried everything others did and nothing worked, can anyone help me??? It took me 2 weeks to set this up but it’s totally worthless without gallery thumbnails 🙁

I installed the Nextgen Gallery, but when I upload pictures to Galleries, thumbnails don’t show up, neither @ “Manage Galleries” in the WP backend nor on the Blog (if you click, the big pictures do show up). My Webspace is big enough!
I uploaded all pics already organized in Galleries (max. 36 pics per folder) via FTP and I’m using the “Add Gallery” –> “Import Image Folder” functionality to integrate into nextgen.

thanks a lot in advance!

http://wordpress.org/extend/plugins/nextgen-gallery/