[Geoserver-users] Error adding JPG image

Hello,
I’m a new user and running GeoServer 1.5.0, when I try and add a world file with world location prj and jgw I get the following error :
org.vfny.geoserver.global.ConfigurationException: Could not obtain a reader for the CoverageDataSet. Please check the CoverageDataSet configuration!
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If I convert the image to a tiff and use the same prj and change the extension of the world file to tfw it all load no problem into geoserver?

I couldnt get it to load as a png either with its world file as well ?

I could get the png file to load if I used the example usa meta & prj file. Is there anything special one has to do to get the world files to work with png and jpg images ?