Delete Excel Sheets With Name Criteria

Dear All

I have a code to delete excel sheets having a common Criteria in their Names Like T10, T12, T16 and so on
I want the code to delete these sheets, the code is working on VBA but it does not on vb.net ??

My Code is
g

Code:

 Private Sub DeleteTSheets()

        Dim xl As New Excel.Application

        Dim wb As Excel.Workbook

        Dim ws as Excel.Worksheet

        wb = xl.Workbooks.Open("C:\Patches\Main_Final.xlsm")

        For Each ws in wb.sheets

           If InStr(1, wb.Sheets(i).Name, "T") Then

              If len(ws.name)=3 then

                   ws.delete()

              End If

           End If

        Next

       End Sub

So, What is wrong exactly?

Thanks, Regards

Moheb Labib