WCF REST服务不能识别URI参数

我正在尝试开发一个与WCF服务交互的android应用程序。我查看了可能发送的格式，但服务似乎无法识别参数并调用指定的函数。

WCF代码:

public interface IEmployeeService
     {
    [OperationContract]
    [WebGet(UriTemplate = "/GetEmployees/{LocationId}/{SessionId}/{CompanyId}", 
    BodyStyle = WebMessageBodyStyle.WrappedRequest,
    ResponseFormat = WebMessageFormat.Json,
    RequestFormat = WebMessageFormat.Json)]
    List<Employee> GetEmployees(string LocationId,string SessionId,string CompanyId);}

Android侧代码:

          DefaultHttpClient client = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(url);
            httpGet.setHeader("Accept", "application/json");
            httpGet.setHeader("Content-type", "application/json");
            try {
                HttpResponse execute = client.execute(httpGet);
                HttpEntity responseEntity = execute.getEntity();

                Reader employeeReader = new InputStreamReader(execute.getEntity().getContent());
                char[] buffer = new char[(int) execute.getEntity().getContentLength()];
                //fill the buffer by the help of reader
                employeeReader.read(buffer);
                //close the reader streams
                employeeReader.close();

它生成的URI是这样的:EmployeeService.svc/GetEmployees/1311000032/2014/1312

，我也尝试了其他格式(如/GetEmployees/?LocationId={LocationId}&SessionId={SessionId})

我已经使用控制台应用程序检查了服务，并将参数传递给服务的引用，得到了正确的结果。但是使用URI什么也不返回。