吐血急求 dwr调用带返回值的方法得不到返回值问题

各位高手请指教，我最近在项目上用到了dwr，一个简单的测试例子都不能通过。
dwr.xml的配置。

<!DOCTYPE dwr PUBLIC

    "-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN"

    "http://www.getahead.ltd.uk/dwr/dwr10.dtd">



<dwr>

	<allow>

		<create creator="new" javascript="workDateServer">

			<param name="class" value="com.nstc.workdate.server.WorkDateServerDWR" />

			<include method="isWorkDate"/>

		</create>

		<convert converter="bean" match="java.lang.StackTraceElement" />

	</allow>

</dwr>

对应的Java类

public class WorkDateServerDWR implements Serializable {





	private static final long serialVersionUID = -4333180125204704841L;



	public String isWorkDate(String selectedDate,String flag){

		System.out.println("======================WorkDateServerDWR start=====================");

		//默认为都是工作日

		String isWork="YES";

		if("1".equals(flag)){

			isWork="NO";

		}

		System.out.println("======================isWork is====================="+isWork);

		System.out.println("======================WorkDateServerDWR end=====================");

		return isWork;

	}

}

jsp页面

<script src='dwrWorkDate/interface/workDateServer.js'></script>

<script src='dwrWorkDate/engine.js'></script>

<script src='dwrWorkDate/util.js'></script>





function fun2(obj){

		obj.blur();

		var workDateReturn=document.getElementById("workDateReturn");

		alert(workDateReturn.value);

		

		var a=test();

		alert("test dwr return is :"+a);

		

		alert(workDateReturn.value);

}

function test(){

    	var _data = "";

   

    	this.isWorkDate = function()

    	{

        	//设置成同步

        	DWREngine.setAsync(false);

        	//调用Java类Test的getString方法，callBackFun为回调函数

        	workDateServer.isWorkDate(function(data){_data = data;},"123","1");

        	//重新设置为异步方式

        	DWREngine.setAsync(true);

        	

        	return _data;

   	 	}

    	

        return _data;

}

部署环境为weblogic81，jdk1.4.2-05
在页面调用 fun2（obj）时始终不能得到返回值。后台不报错，即alert("test dwr return is :"+a);的显示结果为
test dwr return is :
求各位大虾帮忙，到底是什么原因导致出现这样的情况，项目需要，急。