First I recommend you to start by checking if your form works in the browser with JavaScript disabled: remove all cookies for this site, disable JavaScript and try to submit your form.

If the problem is not in JavaScript you need to try to add button => ... to your code. Many sites expects x and y coordinates of the submit button you click:

$mech->submit_form(
    with_fields => {
        "login_username" =>'username',
        "login_password" => 'password',
        "prefLanguage" => '00000000',
    },
    button => "your_submit_button_name",
);

[download]
to your code. Many sites expects x and y coordinates of the submit button you click:

In reply to Re: Seeking assistance with WWW::Mechanize Form Submission by Gangabass
in thread Seeking assistance with WWW::Mechanize Form Submission by tspang

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.