if($bday!=$password) {
                showmessage('credits_addfunds_succeed');
        }

        <tr>
        <td class="altbg1"><span class="bold">{lang birthday}</span></td>
        <td class="altbg2"><div class="input"><input type="text" name="bday" id="bday" size="25" onclick="showcalendar(event, this)" onfocus="showcalendar(event, this);if(this.value=='0000-00-00')this.value=''" value="0000-00-00" onBlur="checkbirth()></div><div id="checkbirth"></div></td>
        </tr>

function checkbirth(){
                var bd = document.register.bday.value;
                var bd2 = $('checkbirth');

                        warning(bd2,profile_seccode_invalid);
                return;
        }