OK ... if the function is not available, you can change following lines in the file include(.)php:
FROM:
//image dimensions
$dimensions = GetImageSize(WB_URL.$dir.'/'.$image);
echo '<img src="'.WB_URL.$dir.'/'.$image.'" '.$dimensions[3].'>';
TO:
//image dimensions
echo '<img src="'.WB_URL.$dir.'/'.$image.'>';
I haven't tested it though ...
cheers
Klaus