When processing pixels, you have an error which looks like this:
Please wait.. Processing the Grid image with GD
Fatal error: Call to undefined function: imagegif()
You have the GD Library installed, all the permissions are correct and you have set the 'server path to admin' setting in Main Config to the recommended settings.
It looks like the GD Library is old, and does not support GIF. (Some older versions did not support GIF because of a patent infringement)
Try changing the output to PNG or JPEG in the Main Config.
A better solution would be to upgrade your GD Library