TextWrap php->pdf problem

Hi to all,
does anybody knows why AddTexWrap of the
class.pdf.php lib is not working?
The text is displayed in one line, without wrapping.



include 'class.pdf.php';
$pdf =& new Cpdf();
$pdf->selectFont('./fonts/Helvetica');

$pdf->AddTextWrap(0,700,300,10,"The Portable Document Format (PDF) is
the file format created by Adobe Systems in 1993 for document exchange.
PDF is used for representing two-dimensional documents in a
device-independent and display resolution-independent fixed-layout
document format. Each PDF file encapsulates a complete description of a
2-D document (and, with Acrobat 3-D, embedded 3-D documents) that
includes the text, fonts, images, and 2-D vector graphics that compose
the document.");

$pdf->stream();
?>

Regards Knut