自定义导出reportviewer到excel文件

我想在单击按钮后将报表查看器导出为excel文件，并隐藏现有的可用于报表查看器的导出工具条按钮。

下面是我的ExportFile函数的代码:

 private void ExportFile()
    {
  SaveFileDialog saveFileDialog1 = new SaveFileDialog();
        saveFileDialog1.Filter = "*PDF files (*.pdf)|*.pdf|Excel files (*.xls)|*.xls|Doc files      (*.doc)|*.doc";
        // Variables
        Warning[] warnings;
        string[] streamids;
        string mimeType;
        string encoding;
        string extension;
        string path = " ";
        DialogResult dr = saveFileDialog1.ShowDialog();
        path = saveFileDialog1.FileName;
        byte[] bytes = reportViewerForm.reportViewer1.LocalReport.Render("Excel", null, out   mimeType, out encoding, out extension, out streamids, out warnings);
        FileStream fs = new FileStream(path + ".xls", FileMode.Create);
        fs.Write(bytes, 0, bytes.Length);
        fs.Close();}

button_click事件代码:

private void btnExport_Click(object sender, EventArgs e)
    {
        this.GetData();
        this.ExportFile();
    }

然而，当我试图导出它时，我得到一个异常错误。下面是我的内部异常:

 InnerException: Microsoft.ReportingServices.ReportProcessing.ReportProcessingException
   Message=One or more parameters required to run the report have not been specified.
   Source=Microsoft.ReportViewer.Common
   ExceptionLevelHelpLink=http://go.microsoft.com/fwlink/?LinkId=20476&EvtSrc=Microsoft.ReportingServices.Diagnostics.Utilities.ErrorStrings&EvtID=rsParametersNotSpecified&ProdName=Microsoft%20SQL%20Server%20Reporting%20Services&ProdVer=1.0
   SkipTopLevelMessage=false
   StackTrace:
        at Microsoft.ReportingServices.ReportProcessing.ReportProcessing.RenderReport(IRenderingExtension newRenderer, DateTime executionTimeStamp, ProcessingContext pc, RenderingContext rc, IChunkFactory cacheDataChunkFactory, IChunkFactory yukonCompiledDefinition, Boolean& dataCached)
        at Microsoft.Reporting.LocalService.CreateSnapshotAndRender(CatalogItemContextBase itemContext, ReportProcessing repProc, IRenderingExtension renderer, ProcessingContext pc, RenderingContext rc, SubreportCallbackHandler subreportHandler, ParameterInfoCollection parameters, DatasourceCredentialsCollection credentials)
        at Microsoft.Reporting.LocalService.Render(CatalogItemContextBase itemContext, Boolean allowInternalRenderers, ParameterInfoCollection reportParameters, IEnumerable dataSources, DatasourceCredentialsCollection credentials, CreateAndRegisterStream createStreamCallback, ReportRuntimeSetup runtimeSetup)
        at Microsoft.Reporting.WinForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, PageCountMode pageCountMode, CreateAndRegisterStream createStreamCallback, Warning[]& warnings)
   InnerException: 

我漏掉了什么参数?任何帮助都将不胜感激。谢谢你。