The code you see at the end give me a blank page. If I remove the IMG tag at the beginning, it works.
Someone can tell me why? It is not the image, because I've used the logo.png I've found in the examples.
--
<?
$content='<table width="80%">
<tr>
<td width="60%"><img src="./res/logo.png"></td>
<td align=><h1>Milano, 26/4/2013</h1></td>
</tr>
<tr>
<td></td>
<td><b>Spett.le TAO DUE srl<br>
Via Pompeo Magno, 1<br>
08747881004<br>
06/3222016<br>
<br></b></td>
</tr>
<tr>
<td><h1>Per Mattia Puglia</h1></td>
<td></td>
</tr>
<tr>
<td colspan=2><h2>Fornitore: O.C HOTEL ROMA<br>(Via Tiburtina, 1352 - 00131 - Roma / P.IVA 06479441005 / Tel. +39 06 4130161)</h2></td>
</tr>
<tr>
<td colspan=2><h1>Dati della prenotazione</h1><h2>Camera: (N.P.)<br>
Tipo: twin<br>
In: 5/4/2013/ Out: 6/4/2013<br>
Early In: No/ Late Out: No<br>
Fullcredit: Si<br>
Tassa di Soggiorno: € 6.00</h2></td>
</tr>
</table>
';
require_once('/var/www/voucher/html2pdf.class.php');
$html2pdf=new HTML2PDF('P', 'A4', 'it',true,'UTF-8');
$html2pdf->setTestImage(true);
$html2pdf->writeHTML($content);
$html2pdf->Output('');
?>