Your code works fine for me in conjunction with the following html and cgi script:

index.html: 
<!DOCTYPE html>
<html>
  <head><title>Python CGI</title></head>
  <body>

    <form action="cgi-bin/mycgi.pl" method="post">
      <div>
      <label for="name">User Name:</label>
      <input id="name" name="ctl00$cntPlaceHolder$UsernameTextBox" typ
+e="text">
      </div>
      
      <div>
      <label for="password">Last Name:</label>
      <input id="password" name="ctl00$cntPlaceHolder$PasswordTextBox"
+ type="password">
      </div>

      <div>
      <input type="submit" value="submit">
    </div>

    </form>
  </body>
</html>

[download]
mycgi.pl: 
#!/usr/bin/env perl
use CGI; 
use CGI::Carp qw{ fatalsToBrowser };

my $cgi = CGI->new;

print $cgi->header,
      $cgi->start_html('Test Page'),
      $cgi->h4('Params:'),
      $cgi->div('Name: ' . $cgi->param('ctl00$cntPlaceHolder$UsernameT
+extBox')),
      $cgi->div('Password: ' . $cgi->param('ctl00$cntPlaceHolder$Passw
+ordTextBox')),
      $cgi->end_html;

[download]

HTML Code after clicking view source

But what does your program output from the following line:

print $page;

In reply to Re: WWW::Mechanize - Unable to fill password field by 7stud
in thread WWW::Mechanize - Unable to fill password field by doubledecker

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.