Multiple concurrent webservice calls to same operation

Question

I'm having a problem trying to call the same web service
operation twice with different parameters. The call is being
executed twice (I'm passing token data to differentiate the calls
in the event handler), but the second call's parameters are
overwriting the first ones. Here is the code:
wsCodeList["GetTupleList"].arguments.TupleName = "BUSTYPE";
var call:Object = wsCodeList["GetTupleList"].send();
call.destination = "busType";
wsCodeList["GetTupleList"].arguments.TupleName = "ENTTYPE";
call = wsCodeList["GetTupleList"].send();
call.destination = "entityType";
mxml:
<mx:WebService id="wsCodeList"
wsdl="
http://simulacrum.hallmarkins.net/ProgramQuoter/codeList.wso?wsdl"
useProxy="false" result="onCodeListResult(event)">
<mx:operation name="GetTupleList" resultFormat="e4x"/>
</mx:WebService>
handler:
private function onCodeListResult(oEvent):void
var call:Object = oEvent.token;
var xmlResult:XMLList = oEvent.result;
trace(call.destination);
if (call.destination == "busType")
busType.dataProvider = xmlResult..mspace::description;
if (call.destination == "entityType")
entityType.dataProvider = xmlResult..mspace::description;
I'm getting back only the expected result for the call with
TupleName "ENTTYPE" twice. So it seems that the parameter is
getting overwritten before the call has gone out. What am I doing
wrong?
Thanx,
OLIVER

Answer 1

Called sequentially (from my original post):
wsCodeList["GetTupleList"].arguments.TupleName = "BUSTYPE";
var call:Object = wsCodeList["GetTupleList"].send();
call.destination = "busType";
wsCodeList["GetTupleList"].arguments.TupleName = "ENTTYPE";
call = wsCodeList["GetTupleList"].send();
call.destination = "entityType";
The docs seem to say this is allow and example found online
do similar, except the arguments are passed as a parameter to send.
This doesn't work for me though. The web service I'm using will
only take the arguments using the arguments object.