[Perl] perldoc and perl/tk

[Offer Kaye]

Hi all,
Running from the command line "perldoc Tk" doesn't work, although using "use
Tk;" in a Perl script does work, for example:
#################################################
#!/usr/bin/perl -w
use Tk;
$top = MainWindow->new();
$top->title ("Simple");

$l = $top->Label(text   => 'hello',
                 anchor => 'n',
                 relief => 'groove',
                 width  =>  10, height => 3);
$l->pack();
MainLoop();
#################################################

The above script works fine, i.e. Perl/Tk is installed okay. So why can't I
access the documentation?
I'm working from Mandrake 9.0, using the default supplied Perl install
(5.8.0).

Thanks in advance,
Offer Kaye