The installed version of PHP GD does not support image rotations. It was probably compiled using the official GD libraries from <a href="http://www.libgd.org">http://www.libgd.org</a> instead of the GD library bundled with PHP. You should recompile PHP --with-gd using the bundled GD library. See <a href="http://www.php.net/manual/en/image.setup.php">PHP Manual</a> for more information. A slower implementation of imagerotate() written in PHP will used in the interim.