cURL script not executing in Rules custom PHP field

using encoding.com to transcode an uploaded video - once this works, I will populate the source with the path to the CCK video that is uploaded

the script works fine when run from Devel Execute PHP

the trigger (Content is Saved) is happening, I get a custom screen message set as an an action with greater wheight than custom PHP

(xxxx blanks out sensitive fields)

function sendRequest($xml)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "http://manage.encoding.com/");
    curl_setopt($ch, CURLOPT_POSTFIELDS, "xml=" . urlencode($xml));
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    return curl_exec($ch);
} 
	// Preparing XML request
   
    // Main fields
    $req = new SimpleXMLElement('<?xml version="1.0"?><query></query>');
    $req->addChild('userid', 'xxxx');
    $req->addChild('userkey', 'xxxx');
    $req->addChild('action', 'AddMedia');

	//source
	$req->addChild('source', 'http://xxxx/sites/default/files/videostmp/bear.flv');

	$lastslash = strripos($req->source,'/') + 1;
	$flv = substr($req->source,$lastslash).".flv";
	$jpg = substr($req->source,$lastslash).".jpg";
	
	//notification method	
	$req->addChild('notify', "xxxx");

	//video format attributes
	$video = $req->addChild('format');
	$video->addChild('output', "flv"); //output filetype
	$video->addChild('destination', 'ftp://xxxx/www/sites/default/files/transcoded/'. $flv); //output destination
	$video->addChild('size','320x240'); //size
	$video->addChild('bitrate','256k'); //bitrate
	$video->addChild('audio_bitrate','64k'); //audio bitrate
	$video->addChild('audio_sample_rate','44100'); //audio sampling rate
	$video->addChild('audio_channels_number','2'); //audio channels
	$video->addChild('framerate','15'); //frame rate
	$video->addChild('two_pass','no'); //use two-pass?
	$video->addChild('cbr','no'); //use constant bit rate?
	$video->addChild('deinterlacing','no'); //use deinterlacing?
	$video->addChild('add_meta','no'); //add meta data?

	$logo = $video->addChild('logo');
	$logo->addChild('logo_source', 'xxxx.png');
	$logo->addChild('logo_x', '0');
	$logo->addChild('logo_y', '0');
	$logo->addChild('logo_mode', '0');
	$logo->addChild('logo_threshold', 'ff0000');

	$thumb = $req->addChild('format');
	$thumb->addChild('output', 'thumbnail');
	$thumb->addChild('time', '3');
	$thumb->addChild('width', '160');
	$thumb->addChild('height', '112');
	$thumb->addChild('destination', 'ftp://xxxx:xxxx@xxxx/www/sites/default/files/transcoded/'. $jpg);	
    
	// Sending API request
        $res = sendRequest($req->asXML());
	exit;