New Post: RE: Invalid Cast Exception

My apologies for the delay. The message text I am getting reads as follows:

Details:

[Invalid Cast Exception]: Unable to cast COM object of type 'System._ComObject' to interface type 'Microsoft.Office.Interop.Excel._Workbook'.
This operation failed because the Query Interface call on the COM component for the interface with IID '{000208DA-0000-0000-C000-000000000046}'
failed due to the following error: Library not registered. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED)).

at System.StubHelpers.StubHelpers.GetCOMIPFromRCW(Object objSrc, IntPtr pCPCMD, IntPtr&pptTarget, Boolean& pfNeeds release)
at Microsoft.Office.Interop.Excel._Workbook.get_Sheets()
at Smrf.AppLib.ExcelUtil.TryGetWorksheet.(Workbook workbook, String worksheetName, Worksheet&worksheet)
at Smrf.AppLib.ExcelTableUtil.TryGetTable.(Workbook workbook, String worksheetName, String tableName, ListObject&Table)
at Smrf.NodeXL.ExcelTemplate.PerWorkbookSettings.TryGetPerWorkbookSettingsTable(ListObject& oPerWorkbookSettingsTable)
at Smrf.NodeXL.ExcelTemplate.PerWorkbookSettings.GetAllSettings()
at Smrf.NodeXL.ExcelTemplate.PerWorkbookSettings. TryGetValue(String settingName, Type value Type, Object&value)
at Smrf.NodeXL.ExcelTemplate.PerWorkbookSettings.get_WorkbookSettings()
at Smrf.NodeXL.ExcelTemplate.NodeXLApplicationSettingsBase.GetWorkbookSettings()
at Smrf.NodeXL.ExcelTemplate.NodeXLApplicationSettingsBase.CopyWorkbookSettingsToStandardSettings()
at Smrf.NodeXL.ExcelTemplate.NodeXLApplicationSettingsBase.get_Item(String propertyName)
at Smrf.NodeXL.ExcelTemplate.GraphMetricUserSettings.get_GraphMetricsToCalculate()
at Smrf.NodeXL.ExcelTemplate.GraphMetricUserSettings.ShouldCalculateGraphMetrics(GraphMetricsgraphMetrics)
at Smrf.NodeXL.ExcelTemplate.CalculateGraphMetricsContext.ShouldCalculateGraphMetrics(GraphMetricsgraphMetrics)
at Smrf.NodeXL.ExcelTemplate.OverallMetricCalculator2.TryCalculateGraphMetrics(|Graphgraph,CalculateGraphMetricsContext calculateGraphMetricsContext,
GraphMetricColumn[]&graphMetricColumns)
at Smrf.NodeXL.ExcelTemplate.GraphMetricCalculationManager.CalculateGraphMetricsAsyncInternal(CalculateGraphMetricsAsyncArgs
oCalculateGraphMetricsAsyncArgs,BackgroundWorker oBackgroundWorker_DoWorkEventArgs oDoWorkEvent Args)
at Smrf.NodeXL.ExcelTemplate.GraphMetricCalculationManager.BackgroundWorker_DoWork(Objectsender, DoWorkEventsArgs e)
at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventsArgs e)
at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)

That's all (!) that was in the error message.
Scott