I've never seen that particular error, but if the command-line tools work and the perl tools don't, it's nearly always because the installations of Imagemagick and Perlmagick don't match.

If you installed IM from the source, try installing the version of Perlmagick in the same package, with a configuration that corresponds to what you used for IM. If you didn't, then may Allah smile upon your unworthy brow, for you are about to start :)