Calling ASP-Actions by WWW::Mechanize (PERL)

Question

i need to parse through a list generated by an ASP action (LoadDialog) and i have no clue how to get it done. If I execute the following i simply get an empty HTML file.

#!/usr/bin/perl -w
#
#
use strict;
use WWW::Mechanize;
use HTTP::Cookies;

my $url = "http://MYURL/LOGIN";
my $appurl = "http://MYURL/SOME.asp"; 

#SOME.asp calls http://MYURL/SOME.asp?Action=LoadDialog" to get results

my $username = 'username';
my $password = 'password';

#login to site 
my $mech = WWW::Mechanize->new();
$mech->cookie_jar(HTTP::Cookies->new());
$mech->get($url);
$mech->form_name('login');
$mech->field(UserName => $username);
$mech->field(Password => $password);
$mech->click();

# get results from LoadDialog (?!)
$mech->get($appurl);
my $app_content = $mech->content();
print "$app_content\n";

Firebug tells me that ?Action=LoadDialog is getting called by the mentioned URL, but Mechanize doesnt realize it (guessing).

Simply chaning $myappurl to http://MYURL/SOME.asp?Action=LoadDialog gives me an empty HTML file as well.

Is there any chance to get the ASP generated content? I cant use any other Perl modules which "run a browser", I need to find a solution usable in a shell.

Thanks in Advance, Marley