About OpenX AdServer: How to make Direct Selection with XML-RPC?

Question

Hi,

I'm trying to retrieve a Banner from a remote OpenX adServer with XMLRPC.

I had been working with the OA_XmlRpc Class . This class has a view function to retrieve a banner specifying bannerid, campaignid or zoneid.

If I call the function in this way, it works:

$oaXmlRpc = new OA_XmlRpc('adsxxxxxxxx.com.ve', '/xxxxxxx/www/delivery/axmlrpc.php', 0, false, 15);

$adArray = $oaXmlRpc->view('zone:251', 0, '', '', 0, $OA_context);

But I want to make Direct selection, so I must only specify the campaignid.

I tried with campaignid:10 in the zoneid:28, but it doesn't retrieve anything

 $adArray = $oaXmlRpc->view('zone:28', 10, '', '', 0, $OA_context);

I'm sure that the campaignid and zoneid exist.

Do you have any idea what could be wrong?