i have created form submission page like "contact page" please find the code below. while i submit form it automatically one blank page created in admin sitetree. i have no luck to find the error, big strange for me. any help me to find this solution it very useful to me

<?php
/**
* Defines the ContactPage page type
*/

class ContactPage extends Page {
   static $db = array(
      'FirstName' => 'Varchar(100)', //
      'Surname'   => 'Varchar(100)',
      'Email' => 'Varchar(100)' //Text presented after submitting message
      
   );
static $has_one = array(
);

}

class ContactPage_Controller extends Page_Controller {
   
   function Form() {
         return new Form($this, "Form", new FieldSet(
   
            // List your fields here
            new TextField("FirstName", "First name"),
            new TextField("Surname"),
            new EmailField("Email", "Email address")
   
         ), new FieldSet(
   
            // List the action buttons here
            new FormAction("SignupAction", "Sign up")
   
         ), new RequiredFields(
   
            // List the required fields here: "Email", "FirstName"
   
         ));
      }

   function SignupAction($data, $form) {

      // Create a new Contact and load the form data into it
      $Contact = new ContactPage();
      $form->saveInto($Contact);

      // Write it to the database. This needs to happen before we add it to a group
      $Contact->write();
      
   }
   
}
?>

Regards,
thisIsRam