Why my register form don't accept spry validation in dw?

Here is my code:

<?php
if(isset($_POST['go_register']))
{
    $last_login=jdate('Y/n/j ,H:i:s');
    $firstname=trim($_POST['firstname']);
    $lastname=trim($_POST['lastname']);
    $email=trim($_POST['username']);
    $password=sha1($_POST['password']);
    $register_date=$_POST['register_date'];
    if(!empty($firstname)&&
        !empty($lastname)&&
        !empty($email)&&
        !empty($password)&&
        !empty($register_date)){


$reg_query="insert into users(firstname,lastname,email,password,register_date,last_login)values('$firstname','$lastname','$email','$password','$register_date','$last_login')";
$reg_result=mysqli_query($connection,$reg_query);
if($reg_result){
    echo "ok";
}
        }//end of not empty
}//end of isset
?>


<div  class="sectionclass">
<script src="../SpryAssets/SpryValidationTextField.js" type="text/javascript"></script>
<link href="../SpryAssets/SpryValidationTextField.css" rel="stylesheet" type="text/css">

  <h2>??? ??? ???</h2>
  <form  method="post" action="<?php echo $_SERVER['PHP_SELF']."?catid=2"; ?>">

    <div>
      <span style="color:#F00">*</span> <label>??? </label>
      <span id="sprytextfield1">
      <input type="text" name="firstname" />
      <span class="textfieldRequiredMsg">A value is required.</span></span></div>

    <div>
      <span style="color:#F00">*</span>  <label>??? ????????</label><input type="text" name="lastname" />
    </div>

    <div>
      <span style="color:#F00">*</span>  <label>??? ??????(?????)</label><input  dir="ltr" type="text" name="username" />
    </div>
    <div>
      <span style="color:#F00">*</span>  <label>??? ????</label><input type="password" name="password" />
    </div>
    <input type="hidden" name="register_date" value="<?php echo jdate('Y/n/j'); ?>">


    <div>
      <input type="submit" name="go_register"  value="??? ???"/>
    </div>

  </form>
</div>
<script type="text/javascript">
var sprytextfield1 = new Spry.Widget.ValidationTextField("sprytextfield1");
</script>