Description
In PHP version 5.3.3+ watermark functions work in a different way which causes images to disappear if watermark is enabled.
Solution
http://www.viart.com/downloads/image_functions-4.2.zip
Download the file above and extract 'image_functions.php' in the /includes folder of your shop replacing existing file. Please do not forget to make a backup copy of the current file in case something goes wrong.