Description:
------------
Trying to validate a valid XML (AltovaXML commandline & Liquid XML Studio says that) I got a "local complex type:The content type
must specify a particle." error... 

Reproduce code:
---------------
$xmlString= '<?xml version="1.0"?>
<OTA_AirAvailRQ xmlns="http://www.opentravel.org/OTA/2003/05"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    TimeStamp="2009-02-18T16:24:59" MaxResponses="5"
Target="Production"
    Version="2008.02" SequenceNmbr="1" EchoToken="960"
    xsi:schemaLocation="http://www.opentravel.org/OTA/2003/05
                        http://www.opentravel.org/2008B/OTA_AirAvailRQ.xsd">
    <POS>
        <Source PseudoCityCode="IPCC" />
    </POS>
    <OriginDestinationInformation>
        <DepartureDateTime>2009-03-10T20:00:00</DepartureDateTime>
        <OriginLocation LocationCode="TNR" />
        <DestinationLocation LocationCode="OLB" />
    </OriginDestinationInformation>
    <TravelPreferences MaxStopsQuantity="2" />
</OTA_AirAvailRQ>';

$xdoc = new DomDocument();
$xdoc->loadXML($xmlString);
$xdoc->schemaValidate("http://www.opentravel.org/2008B/
OTA_AirAvailRQ.xsd"); 

Expected result:
----------------
A "valid schema" result

Actual result:
--------------
Warning : "local complex type:The content type
must specify a particle."