The ExtractWFSData assumes that the name of the WFS Typename is exactly the 
same as the WMS Layername. This is true for Mapserver, but for other OGC 
situations this is not always the case.

It should be like the following:
the TYPENAME should be retrieved from the DescribeLayer response

Example DescribeLayer resonse:

  <?xml version="1.0" encoding="UTF-8" ?> 
- <WMS_DescribeLayerResponse version="1.1.0">
- <LayerDescription name="0" 
wfs="http://192.168.3.107:8080/ImsOgcAdapter/servlet/ImsOgcAdapter?
serviceName=gemeentes">
  <Query typeName="0" /> 
  </LayerDescription>
  </WMS_DescribeLayerResponse>

piece of code I am referring to:
            if ( strpos( $szUpperCase, "TYPENAME=" ) === false )
                $szWFSConnection .= "TYPENAME=".$szSelectedLayerName."&";