Dim LastRow As Long

Dim objExcelWbk As Microsoft.Office.Interop.Excel.Workbook
Dim objExcelsht As Microsoft.Office.Interop.Excel.Worksheet
Dim objExcelApp As Application = System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application")

        With objExcelsht
            While objExcelsht.Cells(rw, 2).value IsNot Nothing
                Dim test As String = objExcelsht.Cells(rw, 2).value.ToString
                rw = rw + 1
            End While
            LastRow = rw - 1
        End With

Dim tgtcolm As Integer 
Dim tgtcell As String
Dim LstBaseColm As Integer       

'----------------------------------  searching tgtcolm -------------------------------
        tgtcell = objExcelsht.Cells(1, 1).Value
        While tgtcell <> ""
            tgtcolm = tgtcolm + 1
            tgtcell = objExcelsht.Cells(1, tgtcolm).Value
        End While
        LstBaseColm = tgtcolm
        'tgtcolm = tgtcolm + 1

Dim LastRwColm As String

LastRwColm = objExcelsht.Cells(dumparrlCnt, tgtcolm + 1).Address(RowAbsolute:=False, ColumnAbsolute:=False)