Unfortunately, I don't remember all I did to get it working, but one thing I did was to add more stuff in the apache2.conf file than suggested in the docs.
Whether or not I *needed* to is another question, but for what its worth, this is what I said:
Alias lxr /var/lib/lxr/http
PerlSetEnv PERL5LIB lib
Also, are there any errors in your apache log?