NULL parameter on javascript call to webservice

Question

I've been following this example from IBM to call a java web service from javascript in an html page http://www.ibm.com/developerworks/webservices/library/ws-wsajax/

a small code snippet to show the communication with the webservice is:

var call = new WS.Call('http://localhost:8080/MICE_Server/MapEditorService'); 
var nsuri = 'http://WebServices/';
var qn_op = new WS.QName('sayHello',nsuri);
var qn_op_resp = new WS.QName('sayHelloResponse',nsuri);  
call.invoke_rpc(qn_op, new Array({name:'name',value:'JOHN'}), null, someCallBackFunction);

The call is being made to the webservice and the webmethod is being executed on the server side, but the parameter being sent is NULL and not the value it's supposed to be. any ideas what might be going wrong?