Helps New boy

[NiCbaZ]

<?php
$contact_name = $_POST['name'];
$contact_email = $_POST['email'];
$contact_subject = $_POST['subject'];
$contact_message = $_POST['message'];

if( $contact_name == true )
{
$sender = $contact_email;
$receiver = "contact@idigcomputers.com";
$client_ip = $_SERVER['REMOTE_ADDR'];
$email_body = "Name: $contact_name \nEmail: $sender \nSubject: $contact_subject \nMessage: $contact_message \nIP: $client_ip \nFlash Contact Form ";
$extra = "From: $sender\r\n" . "Reply-To: $sender \r\n" . "X-Mailer: PHP/" . phpversion();

if( mail( $receiver, "Flash Contact Form - $subject", $email_body, $extra ) )
{
echo "success=yes";
}
else
{
echo "success=no";
}
}
?>

im new to Php and im not sure why this doesnt work, its a contact sheet for my website