Automating sms sending by through Way2sms in Perl

[Cupidvogel]

I am trying to send sms through Way2sms using Perl LWP. The login part is being successful, after which I save the cookies to a local file. The welcome page after being logged in shows a Send SMS link, clicking on which one is redirected to another page with two inputs for mobile number and sms text and a button for submitting and sending the sms. Firebug reveals the page structure, from the Iframe url and the form's action attribute, I constructed the form action's absolute URL and submit the form accordingly, with the cookie stored in the file. However, the sms isn't sent. What I am doing wrong here? The code is as follows. (The name attributes for the two text inputs are correct, taken by observing the source code in Firebug)

use LWP::UserAgent;
use HTTP::Cookies;
my $cookie_jar = HTTP::Cookies->new(
file => "cookies.txt",
autosave => 1,
);

my $ua = LWP::UserAgent->new(
    agent =>
      'Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20100101 Firefox
+/14.0.1',
    cookie_jar => $cookie_jar,
);
my $response = $ua->post(
    'http://site2.way2sms.com/contentt/bar/Login1.action',
    {
        username => $user,
        password => $pass,
    }
);

if ( $response->is_redirect ) {
    $response = $ua->get( $response->header('Location') );
    print 5 if $response->decoded_content =~ /Kaustav Mukherjee/i; #pr
+ints it, showing that the login is successful
}   
my $smsresp = $ua->post("http://site5.way2sms.com/jsp/quicksms.action"
+,[MobNo=>$mob,textArea=>'Hello World']);