Excel 2007 :: Monitoring Change In Certain Range At Worksheet?

I wish to monitor a change in a certain columns at some worksheets. I have - after having consulted John Walkenbach' fantastic book Excel 2007 Power programming with VBA - understood how I do to monitor a change in specific worksheet, by using the Intersect-function in the change-event on that particular worksheet. That works fine.

My situation is that I have an application that I start out with a certain number of workheets in a workbook, and in the course of the work that the application does, it now and then adds worksheets, and these worksheets I would like to monitor for change in a special column. I know, by looking at the names of the worksheets which ones of those in the collection that I want to check.

I therefore used, not the Worksheet_Change event but the Workbook_SheetChange. It doesn't work quite well. I guess my question for now would be:

The call to this event looks like this:

Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)

1) How - in what way - should I use the first argument, the "Sh as Object"? Can I/Should I give it a name?

The error message I get when I use an instruction like this:

If Not Intersect(Target, Range(M:M)) Is Nothing Then
'Do Stuff
end if

The method 'Intersect' in the object '_Global' failed

(M is the column that I want to check)