I am trying to install bugzilla optional modules, but get this error:

I tried using
cpan Module::mod_perl2
but with no success as well.
please advise
I'd suggest to install mod_perl2 from Ubuntu repositories:
sudo apt-get install libapache2-mod-perl2
If you're not happy with this, see mod_perl2 documentation - I don't see where it suggests the syntax you're using.
UPDATE: You're doing it all wrong. :) See my answer here