Perl LWP::UserAgent POST with submit button didn't work. Response is the same page

Question

I'm trying to automatize phpBB installation using a Perl script. I'm creating a UserAgent object and set form data for the first form in the installation process:

   # INSTALL STEP ONE ## Welcome to Installation ###################################
    $install_urls[1] = $install_url;
    my @install_form_one = (
        'install'       => 'Install'
    );
    my $ua = LWP::UserAgent->new();
    $ua->timeout(180);
    my $response = $ua->post($install_urls[$i], @install_form_one);
    if ($response->is_success) {
        $check_result = $self->checkResult($i, $response->{_content}, $debug);
    }

----snip----

This is a snip of the first form for phpBB installation with submit button definition

    <form id="install_install" method="post" action="//phpbb1/install/app.php/install">
        <fieldset class="submit-buttons">
            <legend>Submit</legend>
                <input class="button1" name="install" type="submit" value="Install" />
        </fieldset>
    </form>

PhpBB installation process has six different pages with forms to be completed to begin the process, create autorization user, create DB and E-mail configuration.

My goal is to automatize phpBB installation loading each form data and submitting them sending every form using submit buttons and moving between them.

I read LWP::UserAgent and HTTP::Request::Common documentation and I didn't find any error on my code.

I sent the POST and it's successful but it returned the same page instead send SUBMIT and get the second page on the installation process.

Anyone could help me with this issue? What I am doing wrong? I'm sending SUBMIT name and value on UA POST.