GetImageSize-craziness

Hi, I'd like to insert the URL of a picture, it's dimensions an an accompanying text into a database. I enter the URL and the text in a form and post it to a script, the dimensions shall be retrieved by GetImageSize in the second script. That worked well while all URLs were from another Server. I now tried to enter a URL that points to the very same server the script is running on. That strangely didn't work, GetImageSize gave no result. When I entered a path relative to the script (img/picture.jpg) or the absolute path on the server (/home/user3456/www/img/picture.jpg) it worked very well, not when I entered the URL (http://domain/img/picture.jpg). As I said, it worked with http://domain-from-other-server/img/picture.jpg. Is there a reported bug in the PHP 4.3.2 implementation of GetImageSize? Thanks, Bernhard