# Tried this first
$mech->submit_form(
     form_number => 0, 
     fields      => {
        login    => 'myName',
        password    => 'sumPass'
    }
);

# Also tried
$mech->set_visible( $login, $password );
$mech->submit();

# And this
$mech->set_visible( $login, $password );
$mech->click();