Problem with PHP Mail Form

This has been driving me crazy for a week now. I’ve set up many forms using PHP to gather and send data, but I have one now that isn’t working and I can’t get it to work. I tried using the most basic tutorial here http://www.kirupa.com/web/php_contact_form.htm in addition to several others. What happens is that everything acts like it’s working, I get the success message, but no mail ever goes through. I’ve tried this with my e-mail addresses and client e-mails and the result is the same. Are there any suggestions as to what may cause this? I’m running PHP 4, switched back from 5 in case that was the problem, but no change.

Here’s the latest stripped down code I’m trying, with my e-mail address removed.

**Form:
**
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
<html xmlns=“http://www.w3.org/1999/xhtml”>
<head></head>

<form method=“post” action=“mailer.php” >
<p>We’re always interested in feedback or suggestions. Use this form to send us your thoughts and ideas.<br />
<br />
<strong>Name</strong><br />
<input type=“text” name=“name” size=“25” />
<br />
<b><strong>Email address</strong></b><br />
<input type=“text” name=“email” size=“25” />
<br />
</p>
<hr size=“4” noshade=“noshade” />
<br />
<font face=“Century Gothic” size=“3”> <b><strong>Any Comments or Suggestions?</strong> <br />
</b>
<textarea name=“message” rows=“6” cols=“45” wrap=“soft”>
</textarea>
<br />
<br />
<input type=“submit” name=“submit” value=“submit” />
<br />
<br />
<font size=“1”>Hit the ‘back’ button on your browser to return from your confirmation page.</font></font>
</form>

</body>
</html>

PHP script

<?php
if(isset($_POST[‘submit’])) {
$to = “(email removed for privacy)”;
$subject = “Contact Us Message”;
$name_field = $_POST[‘name’];
$email_field = $_POST[‘email’];
$message_field = $_POST[‘message’];

$body = “From: $name_field
E-Mail: $email_field
Message:
$message”;

echo “Data has been submitted to $to!”;
mail($to, $subject, $body);
} else {
echo “There was an error sending data, please go back and try again.”;
}
?>

Thanks in advance for any ideas or suggestions