I am trying to install RT-4.0.5 (Request Tracker) but I keep getting the following output;

$ make fixdeps

<output cut>

SOME DEPENDENCIES WERE MISSING.
CORE missing dependencies:
    DateTime >= 0.44 ...MISSING
make: *** [fixdeps] Error 1

The full output is here (it's quite long); http://pastebin.com/raw.php?i=Tn7GrkYw

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 8.04.4 LTS
Release:    8.04
Codename:   hardy

$ perl --version

This is perl 5, version 14, subversion 2 (v5.14.2) built for i686-linux

$ cpan --version
/usr/local/bin/cpan version 1.57 calling Getopt::Std::getopts (version 1.06 [paranoid]),
running under Perl version 5.14.2.
  [Now continuing due to backward compatibility and excessive paranoia.
   See ``perldoc Getopt::Std'' about $Getopt::Std::STANDARD_HELP_VERSION.]
Nothing to install!

I can't see why this is a problem;

$ cpan DateTime
Going to read '/root/.cpan/Metadata'
  Database was generated on Thu, 08 Mar 2012 16:11:26 GMT
DateTime is up to date (0.72).