Error: eBay does not understand the Picture URL that you provided.
There are a couple reasons why eBay would reject the URL:
1) The URL contains eBay in the address. (Example: http://ebay.myserver.com/image1.jpg)
The idea is to prevent users from linking to images that are on the eBay domain, but it can also block legitimate uses. One workaround is to link to the IP address, instead.
2) The item has the Gallery feature enabled, but no Gallery URL has been defined and the PictureURL image is a .GIF. For licensing reasons, Gallery images cannot be in the .GIF format. If no GalleryURL has been defined, then the PictureURL will be used by default and an error will occur.