AJAX Control Toolkit - AjaxFileUpload 上传问题

[cancancam]

前台代码:

<asp:AjaxFileUpload ID="AjaxFileUpload1" runat="server" ThrobberID="iThrobber" AllowedFileTypes="pdf" MaximumNumberOfFiles="10" OnUploadComplete="AjaxFileUpload1_UploadComplete"/>

后台代码:

protected void AjaxFileUpload1_UploadComplete(object sender, AjaxControlToolkit.AjaxFileUploadEventArgs e)
{
    string filePath = "~/test/" + new FileInfo(e.FileName).Name;
    AjaxFileUpload1.SaveAs(MapPath(filePath));
}

当页面不传递?参数时, 功能正常, 但是如果带?参数时, 则会弹出错误
即:
localhost/upload.aspx 没问题
localhost/upload.aspx?aa=bb 出错


错误: Sys.ArgumentException: Cannot deserialize. The data does not correspond to valid JSON.
Parameter name: data


请帮忙解决, 非常感谢!

[cancancam]

求帮忙呀，谢谢大家