eBay "Please provide the correct information in the highlighted fields."

Just spent two evenings trying to add new ebay items only to keep getting above message every time. By chance discovered reason was because the gallery photo I used had blanks in the name. The name was correct, and when used embedded in description was fine, but when used as first free ebay photo which is then used for gallery it looked fine but caused the above error when I tried to complete process. By getting rid of the blanks, replaced them with hyphen, all was OK!