简单javascript wcf webservice调用在成功时为结果返回null

我试图从javascript中调用一个简单的WCF web服务，返回一个布尔值

我在页面中有scriptmanager

如下所示，在OnAssignSuccess javascript方法中，回调结果始终返回null

如果需要，我可以提供web.config

诊断跟踪显示在根目录中返回的布尔值，但它不是响应的一部分，如下所示

下面是javascript代码

这是诊断跟踪

urn:PT/updatebackupsupersorresponse
好啊
应用程序/json；字符集=utf-8
真的

我使用jquery ajax调用实现了它，如下所示

function OnAssignBackup() {
    var employees = document.getElementById("<%=cmbBackup.ClientID%>");
    $.ajax
        (
            {
                type: 'GET',
                url: '../../Services/PT.svc/UpdateBackupSupervisor',
                data: { backupUserGUID: employees.value },
                success: function (response, status, error) {
                    alert('Successfully Updated Backup Supervisor: ' + status);
                },
                error: function (request, status, error) {
                    alert('Update Backup Supervisor Failed with error: ' + error);
                }
            }
        );
}

函数OnAssignBackup（）{ var employees=document.getElementById（“”）； $.ajax ( { 键入：“GET”， url:“../Services/PT.svc/UpdateBackupSupervisor”， 数据：{backupUserGUID:employees.value}， 成功：功能（响应、状态、错误）{ 警报（'备份主管已成功更新：'+状态）； }, 错误：功能（请求、状态、错误）{ 警报（'更新备份管理器失败，错误：'+错误）； } } ); } 我在web.config中使用webHttp行为

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class PT
{
    [OperationContract]
    [WebInvoke(ResponseFormat = WebMessageFormat.Json)]
    public bool UpdateBackupSupervisor(string backupUserGUID)
    {
        bool bRet = false;
    .
    .
    .
        return bRet;
    }
}

<MessageLogTraceRecord>
<Addressing xmlns="http://schemas.microsoft.com/2004/06/ServiceModel/Management/MessageTrace">
<Action>urn:PT/UpdateBackupSupervisorResponse</Action>
</Addressing>
<HttpResponse xmlns="http://schemas.microsoft.com/2004/06/ServiceModel/Management/MessageTrace">
<StatusCode>OK</StatusCode>
<WebHeaders>
<Content-Type>application/json; charset=utf-8</Content-Type>
</WebHeaders>
</HttpResponse>
<root type="object" xmlns="">
<d type="boolean">true</d>
</root>
</MessageLogTraceRecord>

function OnAssignBackup() {
    var employees = document.getElementById("<%=cmbBackup.ClientID%>");
    $.ajax
        (
            {
                type: 'GET',
                url: '../../Services/PT.svc/UpdateBackupSupervisor',
                data: { backupUserGUID: employees.value },
                success: function (response, status, error) {
                    alert('Successfully Updated Backup Supervisor: ' + status);
                },
                error: function (request, status, error) {
                    alert('Update Backup Supervisor Failed with error: ' + error);
                }
            }
        );
}