[Mediawiki-l] ImageMagick error

[KAndreou at rccl.com]

I've installed the latest version of ImageMagick and I've set the 
appropriate flags in LocalSettings.php:
$wgUseImageMagick = true;
$wgImageMagickConvertCommand = "/usr/local/bin/convert";
$wgUseImageResize = true;

But, on every image that is resized, I get this error:

Error creating thumbnail: convert: no decode delegate for this image 
format `/wwwroot/htdocs/mediawiki/images/5/5f/Image1.jpg'.
convert: missing an image filename 
`/wwwroot/htdocs/mediawiki/images/thumb/5/5f/Image1.jpg/120px-Image1.jpg'.


Any ideas?