Installing W3C markup validator - stuck on step 5

Hi,
I'm trying to set up the validator on my computer at work (it's a Mac) and
I get an error when I do the last part of step 4 (testing the validator
script).
This is the html that it outputs:

<h1>Software error:</h1>

<pre>Can't locate SGML/Parser/OpenSP.pm in @INC (@INC contains:
/Library/Perl/5.16/darwin-thread-multi-2level /Library/Perl/5.16
/Network/Library/Perl/5.16/darwin-thread-multi-2level
/Network/Library/Perl/5.16
/Library/Perl/Updates/5.16.2/darwin-thread-multi-2level
/Library/Perl/Updates/5.16.2
/System/Library/Perl/5.16/darwin-thread-multi-2level
/System/Library/Perl/5.16
/System/Library/Perl/Extras/5.16/darwin-thread-multi-2level
/System/Library/Perl/Extras/5.16) at ./check line 64.

BEGIN failed--compilation aborted at ./check line 64.

</pre>

<p>

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</p>


It seems at first glance that the problem is that part of the DTD library
didn't install correctly, and I'm not really sure how to troubleshoot this.
Thanks for your help!

- Mikkel Sandberg