Error adding worksheet to workbook

Hello,
I've been trying the following code, specifically the copy code but I keep getting an error on the following lind.  I've included the error message details
ws.Copy(Before:=wb.Worksheets(1))

System.Runtime.InteropServices.COMException was unhandled
  ErrorCode=-2146827284
  Message="Exception from HRESULT: 0x800A03EC"
  Source="Microsoft.Office.Interop.Excel"
  StackTrace:
       at Microsoft.Office.Interop.Excel._Worksheet.Copy(Object Before, Object After)
       at BADS.frmMultplePBTMR.btnGenerateReport_Click(Object sender, EventArgs e) in C:\Documents and Settings\jvelasqu\My Documents\Visual Studio 2008\Projects\BADS\BADS\frmMultplePBTMR.vb:line 254
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(ApplicationContext context)
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
       at BADS.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
       at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 

Select all Open in new window

I have no idea what that means, I'm afraid, as I don't know a lot about .Net.

If you notice there are 2 arguments for the Copy method - Before and After, you only seem to be supplying the Before.

I don't know how VB.NET handles missing arguments, but I know C#.NET can be a bit picky - in earlier versions you have to provide every argument or use Missing.

That's about 13 (or is it 15) arguments for something as 'simple' as opening a workbook.

Also Before:= is a named argument, again I don't know how VB.NET (or C#.NET) handles them.

The first thing I would try would be to remove 'Before:='.

Then I would try removing all the argument(s) leaving just (), not quite sure how that would work - in VBA if you don't have any arguments then a new workbook is created with just the copied sheet in it.

Another thing I would try would be to supply both the before and after arguments but I don't quite know how that would work - might be tricky telling the code you want to copy before one worksheet and after another.

Anyway, try those - in no particular order mind you.

I'll check it out myself later.

I was able to get rid of the error by opening both workbooks into the same instance of Excel.  However I am getting a cast error at  ws.Copy(wbkDest.Worksheets(wbkDest.Worksheets.Count - 1)).  I will post a new question regarding this error

 For Each dp As DatasetPair In dpl
            Dim excelApp As New Excel.Application
            Dim ws As New Excel.Worksheet
            ws = GenerateWorksheet(dp)
            ws.SaveAs(wb.Path.ToString)


            Dim strSourceFilePath As String
            strSourceFilePath = wb.Path.ToString & "\" & wb.Name.ToString
            MessageBox.Show(strSourceFilePath)

            'wb.Close()
            Dim wbkDest As Excel.Workbook = excelApp.Workbooks.Open(strFilePath)


            Dim wbkSource As Excel.Workbook = excelApp.Workbooks.Open(strSourceFilePath)
            'ws.Copy(Before:=wbkDest.Worksheets.Count - 1)
            ws.Copy(wbkDest.Worksheets(wbkDest.Worksheets.Count - 1))

           
        Next

Select all Open in new window

Well it might have helped to know there was multiple instances of Excel kicking around.:)

Why do you have more than 1 in the first place?

I can't see anything in the posted code suggesting that would be needed.

Even if you do need more than one instance, are you sure you need one for every iteration of the loop?

Mind you I am just going by what code you've posted - there seems to be a few classes/functions being called/whatever.

That might even be where the cast error is originating, though I can't seem to see any casting in the code.

I removed the mutliple instances of excel after doing some research.  As far as the cast error is concerned,  all I am attempting to do is copy a worksheet to the location defined in the new workbook as worksheets.count - 1

The new question is posted at
http://www.experts-exchange.com/Programming/Languages/.NET/Visual_Basic.NET/Q_26463193.html

What you are trying to do isn't quite relevant to the cast thing as far as I know, it's how you are trying to do it.

Anyway I'll take a look at the other thread.

Since the question had already been closed, I wanted to be able to award points