We're using Telerik.ReportViewer.WebForms.ReportViewer for exporting to another files format but only exported to excel file I got error message below.

please help to advise for this error.

Server Error in '/' Application.
Attempting to get range {22,19}{10,3},Merged=False,Parent=printPackingList2[0], that intersects with an already merged range.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.InvalidOperationException: Attempting to get range {22,19}{10,3},Merged=False,Parent=printPackingList2[0], that intersects with an already merged range.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace: 

 [InvalidOperationException: Attempting to get range {22,19}{10,3},Merged=False,Parent=printPackingList2[0], that intersects with an already merged range.]
   Telerik.Reporting.Excel97.Worksheet.GetRange(Int32 col, Int32 row, Int32 colSpan, Int32 rowSpan) +186
   Telerik.Reporting.ExcelRendering.Excel97.Worksheet.Telerik.Reporting.ExcelRendering.IWorksheet.GetRange(Int32 col, Int32 row, Int32 colSpan, Int32 rowSpan) +73
   Telerik.Reporting.ExcelRendering.RenderingItem.GetRange(IWorksheet worksheet, TableLayoutInfo layoutInfo) +381
   Telerik.Reporting.ExcelRendering.RenderingItem.Render(IWorksheet worksheet, TableLayoutInfo layoutInfo) +78
   Telerik.Reporting.ExcelRendering.RenderingItemContainer.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +141
   Telerik.Reporting.ExcelRendering.Section.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +62
   Telerik.Reporting.ExcelRendering.RenderingItem.Render(IWorksheet worksheet, TableLayoutInfo layoutInfo) +638
   Telerik.Reporting.ExcelRendering.RenderingItemContainer.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +141
   Telerik.Reporting.ExcelRendering.Report.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +786
   Telerik.Reporting.ExcelRendering.RenderingItem.Render(IWorksheet worksheet, TableLayoutInfo layoutInfo) +638
   Telerik.Reporting.ExcelRendering.Report.Render(IWorkbook workbook) +373
   Telerik.Reporting.ExcelRendering.Excel97.ExcelReport.Telerik.Reporting.Processing.IRenderingExtension.Render(Report report, Hashtable renderingContext, Hashtable deviceInfo, CreateStream createStreamCallback, EvaluateHeaderFooterExpressions evalHeaderFooterCallback) +184
   Telerik.Reporting.Processing.ReportProcessor.RenderCore(ExtensionInfo extensionInfo, IList`1 reports, Hashtable deviceInfo, IRenderingContext renderingContext, CreateStream createStreamCallback) +1386
   Telerik.Reporting.Processing.ReportProcessor.RenderCore(String format, IList`1 reports, Hashtable deviceInfo, IRenderingContext renderingContext, CreateStream createStreamCallback) +103
   Telerik.ReportViewer.WebForms.ReportExportOperation.RenderReport(String format, IList`1 processingReports, Hashtable deviceInfo, IRenderingContext renderingContext) +259
   Telerik.ReportViewer.WebForms.ReportRenderOperation.PerformOperationOverride() +340
   Telerik.ReportViewer.WebForms.HandlerOperation.PerformOperation(HttpContext context, ICacheManager cacheManager) +74
   Telerik.ReportViewer.WebForms.BasicHandler.ProcessRequest(HttpContext context) +276
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +341
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69