如何制作PDF支持FPDM？

Does anyone know how I can make a PDF that will work with FPDM to support auto form-filling? Right now I have the following code:

<?php

/***************************
  Sample using a PHP array
****************************/

require('fpdm.php');

$fields = array(
    'name'    => 'Name',
    'address' => 'My address',
    'city'    => 'My city',
    'phone'   => 'My phone number'
);

$pdf = new FPDM('w4_form.pdf');
$pdf->Load($fields, false); // second parameter: false if field values are in ISO-8859-1, true if UTF-8
$pdf->Merge();
$pdf->Output();
?>

And I keep getting the following error: FPDF-Merge Error: Fast Web View mode is not supported.

I tried turning off Fast-Web View in Adobe Acrobat, but I still get the same error. So how can I make this PDF work with FPDM??