It's a little different than that, I think. My MediaWiki is just asking for the location of GD, and when it can't find it, it returns this error:

Code:
Error creating thumbnail: /usr/bin/convert: Unrecognized option (-thumbnail).
In my config file it asks the location of GD, which filled out by deault is /usr/bin/convert. Is there another place where the library could be located, or is there a way that I should notate the directory differently?