Sending multipart MIME mail with inline image

From today morning itself, I'm trying to send a MIME mail with PHP's mail() function that displays an image inline. But, I don't know where the <bleep> I'm making the mistake. The image goes but in GMail it shows up as an attachment instead of getting displayed inline. Here's my source code:

<?php

$to="prab97@indiatimes.com";

$from="help@indiatimes.com";

$subject="Verify";

$boundary="whatever";

$headers="MIME-Version: 1.0\r\n";

$headers.="Content-type: multipart/mixed; 

      boundary=\"$boundary\"\r\n";

$headers.="From: ".$from."\r\n";

$headers.="Reply-To: ".$from."\r\n";

$message = "--$boundary\n";

$message.="Content-type: image/png\n";

$message.="Content-Transfer-Encoding: base64\n";

$message.="Content-disposition: inline\n\n";

$encoded = base64_encode(file_get_contents("image.png"));

$message.=$encoded."\n";

$message.="--$boundary\n";

$message.="Content-type: text/html; charset=\"iso-8859-1\"\n";

$message.="Content-Transfer-Encoding: 7bit\n";

$message.="Content-disposition: inline\n\n";

$message.="This is a test. <a href="test.tst">Test</a>\n";

$message.="--$boundary--";

$send=mail($to, $subject, $message, $headers);

if($send){

echo "Mail was sent successfully!";

}

else {

echo "Failed!!!";

}

?>

I tried multipart/mixed, multipart/alternative, multipart/related but can't succeed in making it display inline. I want the image to be displayed first, followed by html text. There's no clue I'm getting about where I went wrong. If you've any idea then do tell me.