Calling Livecycle ES with mx.rpc.soap.WebService using ActionScript

I have Livecycle ES installed on an application server (not the machine I'm calling from).  I have Flex 3 installed on my machine.  I'm coding up a custom-built Form Guide.  I'm trying to call a process on the Livecycle ES machine with mx.rpc.soap.WebService using ActionScript.  I was able to get it working with just one parameter, but now that I have many parameters it's puking on me.  I have tested the process by invoking from Workspace and it behaves as expected.  When I try it from the formguide/Flex AS I get an IO error.  Here's the pertinent code snippet:

      import mx.controls.Alert;
      import mx.events.FlexEvent;
    import mx.rpc.events.FaultEvent;
      import mx.rpc.soap.LoadEvent;
      import mx.rpc.soap.Operation;
      import mx.rpc.soap.WebService;
      import xfamx.scripting.Xfa;
      import xfamx.utils.XMLUtils;
          
      private var stateService:WebService;
      private var _webServiceLoaded:Boolean = false; // flag noting when wsdl has been loaded
      
      private function initWebService():void {
            if (!stateService) {
                  stateService = new WebService();
                  stateService.wsdl = "http://xxx.xxx.xxx:8080/soap/services/SaveState?wsdl"; // replace this url
                  stateService.addEventListener(LoadEvent.LOAD, load_listener);
                  stateService.addEventListener(FaultEvent.FAULT, fault_listener);
                  stateService.loadWSDL();
                  mx.controls.Alert.show('Initializing WSDL', 'Message');
            }
      }
      private function saveState():void {
            initWebService(); // init webservice
            if (_webServiceLoaded) { // is wsdl is loaded
                  //stateService.setRemoteCredentials("user", "password"); -- This doesn't seem to work anyway.
                  var xmlModel:XML = new XML(Xfa.instance.datasets.saveXML());
                  stateService.invoke.send('00000000-0000-0000-0000-000000000000',false,'',xmlModel..data,'asdf',false,'asdf');
                  mx.controls.Alert.show('State Sent!', 'Message');  // Comment this out later.
            } else { // else
                  callLater(saveState); // wait a frame and try again
            }
      }
      
      public function fault_listener(event:FaultEvent):void {
          mx.controls.Alert.show(event.fault.message, 'Message');
          mx.controls.Alert.show(event.fault.rootCause.toString(), 'Root Cause toString');
          mx.controls.Alert.show(event.fault.toString(), 'fault toString');
      }
      
      public function load_listener(event:LoadEvent):void {
            _webServiceLoaded = true; // mark wsdl as loaded so we know we can use the web service
            mx.controls.Alert.show('Initialized', 'Message');
      }


Generates the following error:

Fault toString:
[RPC Fault faultString="HTTP request error" faultCode="Server.Error.Request" faultDetail="Error: [IOErrorEvent type="ioError" bubbles=false cancelable=false eventPhase=2 text="Error #2032: Stream Error. URL: http://xxx.xxx.xxx:8080/soap/services/SaveState"]. URL: http://xxx.xxx.xxx:8080/soap/services/SaveState"]

Root Cause toString:
[IOErrorEvent type="ioError" bubbles=false cancelable=false eventPhase=2 text="Error #2032: Stream Error. URL: http://xxx.xxx.xxx:8080/soap/services/SaveState"]

When I watch the transaction with Wireshark (PKA ethereal) I see the data send up base64 encoded, and then a 500 error coming back from the server.  So, I assume that I'm not sending the parameters correctly.  But I can't find anything about the correct formatting for sending multiple parameters to a LC ES Process using Flex 2 and ActionScript.  I don't want the mxml equivalent, I want the actionscript method.

I've already read the Adobe docs: http://livedocs.adobe.com/flex/201/langref/mx/rpc/soap/WebService.html  to no avail.

If there is a Flex expert out there, please help.  TYIA