PHP contact form is not working

[CyncCrync]

I'm trying to add a contact form to my website but each time I click send it takes me to a black window and the address bar says contact.php. Also it doesn't redirect back.My website is hosted as an application using the google app engine.I tried literally everything but I can't get it to work.Below is my HTML code:\[code\]<form action="contact.php" method="post"> <p>Your name</p> <input type="text" name="name"/> <p>Your e-mail</p> <input type="text" name="email"/> <p>Message</p> <textarea name="message"></textarea> <input type="submit" value="http://stackoverflow.com/questions/14494340/Send"/> <input type="reset" value="http://stackoverflow.com/questions/14494340/Clear"/></form>\[/code\]and here is my PHP code:\[code\]<?php$field_name = $_POST['name'];$field_email = $_POST['email'];$field_message = $_POST['message'];$mail_to = '[email protected]';$subject = 'Message from a site visitor '.$field_name;$body_message = 'From: '.$field_name."\n";$body_message .= 'E-mail: '.$field_email."\n";$body_message .= 'Message: '.$field_message;$headers = 'From: '.$field_email."\r\n";$headers .= 'Reply-To: '.$field_email."\r\n";$mail_status = mail($mail_to, $subject, $body_message, $headers);if ($mail_status) { ?> <script language="javascript" type="text/javascript"> alert('Thank you for the message.'); window.location = 'contact.html'; </script><?php}else { ?> <script language="javascript" type="text/javascript"> alert('Message failed.'); window.location = 'contact.html'; </script><?php}?>\[/code\]