Extended PHP Class not accepting variables
<p>I am extending FPDF and want to include some external variables but it's not working. What am I doing wrong?</p>

<pre><code>&lt;?php

class PDF extends FPDF {

    public var $DocNum; 
    public var $cliente;
    public var $noCliente; 
    public var $noTienda;
    public var $noPedido;

    function Header() {
        $this-&gt;Image('fpdf/cabMCR.jpg',5,10,100,0,'JPG','');

        $this-&gt;SetFont('Arial','B','16');
        $this-&gt;SetXY(125,15);
        $this-&gt;Write(5,'FACTURA');

        // doing some more stuff here
    }

    function Footer() {
        $this-&gt;SetTextColor(150,150,150);
        $this-&gt;SetXY(10,285);
        $this-&gt;SetFont('Helvetica','I',7);
        $this-&gt;Write (5, 'MCR Electronic S.L. Inscrita en el Registro Mercantil de Madrid en Tomo 15819, folio 163, Seccion 8ª, hoja M-267058, CIF: B82766452');
        $this-&gt;SetTextColor(0,0,0);
    }
}

$pdf=new PDF();

$pdf-&gt;Open();
$pdf-&gt;AddPage('P');
$pdf-&gt;SetDisplayMode(real,'default'); 
$pdf-&gt;SetAuthor('Company S.L');
$pdf-&gt;SetTitle('Factura MCR');

$pdf-&gt;$DocNum = $DocNum;
$pdf-&gt;$cliente = $cliente;
$pdf-&gt;$noCliente = $noCliente; 
$pdf-&gt;$noTienda = $noTienda;
$pdf-&gt;$noPedido = $noPedido;

?&gt;
</code></pre>
