I'm totally banging my head against the wall on this one.
www.artransforms.com/joomla15/index.php?option=com_content&view=category&layout=blog&id=8&Itemid=6
The linked page shows the same files (one with an extra p in the file name). One set of image thumbs shows the other does not. The files and images have the exact same permissions on them. I can actually take an .gif from a gallery where the thumbnail is showing and move it into a different folder where the thumbnails are showing and that one image will have a blank thumbnail (but when it was in the previous gallery it showed up fine and once I move it back it shows up fine).
I would really like to get SIGPro to work on my site and it was working fine when I was selfhosting. Once I transfered over to my webhost then none of my images had thumbnails. I then transferred all my files from my self-hosted site to my webhosted site and most of the thumbnails showed up. The weird thing is, if you click on the thumbnail, the picture shows up just fine.
Here is my previous post on the topic forum.joomlaworks.net/index.php?topic=10427.0 I'm sorry if it's bad etiquette to start a new post but the old one is so long and I've done some additional troubleshooting.

I also tried installing a fresh version of joomla and had the same problem. Click on the thumbnail and you get the image, but no thumbnail image.

The problem doesn't appear in the first folder, which means that the plugin works fine.

However, make sure that all the filenames are web friendly with no spaces or characters other than letters, underscores, or numbers.

The file names are exactly the same between the first set of thumbs that are visible to the second set up thumbs that are not visible.

The problem doesn't appear in the first folder, which means that the plugin works fine.

However, make sure that all the filenames are web friendly with no spaces or characters other than letters, underscores, or numbers.

Hi, I just wanted to let you know what the issue was (and I'm going to post on my original post as well). I believe (at least for SIG Pro for Joomla 1.5) that my PHP version was not as current as it should have been. The documentation says PHP 4 works but, honestly, my site was running on 4.3 (from 2002) and as soon as I switched everything to another host with a more current PHP and had no problems with it whatsoever.