what is wrong in this code

this is the code:

#! Perl\bin\perl

use WWW::Mechanize;
my $mech = WWW::Mechanize->new();

$mech->get( $url );


$mech->follow_link( text_regex => qr/viewtopic/i );
$mech->follow_link( url => 'http://www.google.com/index.html' );

$mech->submit_form(
form_number => 3,
fields => {
username => 'guesthere3',
postbody => 'This is a test',
}
);

$mech->submit_form(
form_name => 'post',
fields => { query =>
'http://www.google.co.uk/search?hl=en&safe=off&q=intitle%3A%22ipod%22+view+f
orum+%22you+can+post+new+topics%22&meta=', },
button => 'submit'
);

This is the error message when I run the code:

Missing base argument at C:/Perl/site/lib/HTTP/Response.pm line 78


.