Getting the count of sheets in debug mode - MS Excel PIA - vb.net

Question

I cannot access .Count property of Sheets. I'm using Excel Interop. I'm in debug mode and I'm trying this:
?xlSheets.Count
This results in:
(1) : error BC30456: 'Count' is not a member of 'Sheets'.
I have no clue on what's wrong, as I see in MSDN that there is such property!
This works well: ?xlSheets(1).Name. But Count fails... Is it possible to get the count of sheets?
These guys had a similar problem - they wanted to .Worksheets.Add(.Worksheets.Sheets.Count). Finally they did not get the count, they went for .Worksheets.Add(After:=.Worksheets(3))...
UPDATE:
To my great delight, after further trying / experimentations, it became clear that in debug modeSheets.Count does not work only when there is no such line in the code.
While debugging this code, I can access Sheets.Count, because this line exists in the code.
Imports Excel = Microsoft.Office.Interop.Excel
Public Class Form1
Dim xlApp As Excel.Application
Dim xlWorkBook As Excel.Workbook
Dim xlWorkbooks As Excel.Workbooks
Dim xlSheets As Excel.Sheets
Private Sub btnCreate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCreate.Click
xlApp = New Excel.Application
xlWorkbooks = xlApp.Workbooks
xlWorkBook = xlWorkbooks.Open("C:\Temp\Template.xlsm")
xlSheets = xlWorkBook.Sheets
MessageBox.Show(xlSheets.Count)
xlWorkBook.Close()
xlApp.Quit()
'Clean Up
releaseObject(xlSheets)
releaseObject(xlWorkBook)
releaseObject(xlWorkbooks)
releaseObject(xlApp)
End Sub
Private Sub releaseObject(ByVal obj As Object)
Try
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj)
obj = Nothing
Catch ex As Exception
obj = Nothing
Finally
GC.Collect()
GC.WaitForPendingFinalizers()
End Try
End Sub
End Class
But when I replace MessageBox.Show(xlSheets.Count) with MessageBox.Show(xlSheets.Creator), the error appears when trying to ?xlSheets.Count. I don't yet know the reason of such behaviour (I come from VBA environment where debug mode seems to be more flexible), but at least that works during run time...
If someone knows how to fix this, please let me know, as I feel restricted while testing small things in debug mode!

Answer 1

Use Project > Properties > References. Locate and select the "Microsoft Excel xx.x Object Library" entry. In the Properties window, set the Embed Interop Types property to False. Use Build > Rebuild to rebuild your app. It will now work the way you expected.
Briefly, this option is a strong optimization for COM interop libraries, like Microsoft.Office.Interop.Excel, you no longer have a runtime dependency on the library. The compiler copies the interop types from the library into your program's executable, only the ones you actually need to run your program. Explains your discovery, the Count property is in fact missing when you don't use it in your program.
You don't want to leave it this way, set the property back to True after you're done testing.

Answer 2

Your code works fine for me. I notice the file type is a macro-enabled workbook. Have you set your macro settings properly on your dev PC? By default Excel will disable macros.
Edit: I think I get your problem now. You are getting the error when trying to print the property in debug mode. Probably you have stopped the code at a point where the variable is not set (.Count is only available while the button code is actually running). Put a breakpoint on the message box line, click the button, and try again.