Export Excel in VB.Net

Imports System.Data.SqlClient
Imports System.Data.OleDb
Imports System.IO
Imports System.Net.Mime.MediaTypeNames
Imports Microsoft.Office.Interop


Dim idx As Integer
    Private Excel03ConString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties='Excel 8.0;HDR={1}'"
    Private Excel07ConString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 8.0;HDR={1}'"

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim rowsTotal, colsTotal As Short

        Dim I, j, iC As Short

        System.Windows.Forms.Cursor.Current = System.Windows.Forms.Cursors.WaitCursor

        Dim xlApp As New Excel.Application

        Try

            Dim btn As Button

            Dim excelBook As Excel.Workbook = xlApp.Workbooks.Add

            Dim excelWorksheet As Excel.Worksheet = CType(excelBook.Worksheets(1), Excel.Worksheet)

            xlApp.Visible = True

            Dim chartRange As Excel.Range

            rowsTotal = DataGridView1.RowCount - 1

            colsTotal = DataGridView1.Columns.Count - 1

            chartRange = excelWorksheet.Range("A1", "G1")

            chartRange.HorizontalAlignment = 3

            chartRange.VerticalAlignment = 3

            chartRange.Interior.Color = System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.Yellow)

            chartRange.Font.Color = System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.Red)

            chartRange.Font.Size = 20

            chartRange = excelWorksheet.Range("A1", "G1")

            chartRange.Font.Bold = True

            chartRange = excelWorksheet.Range("A1", "G1")

            chartRange.Font.Bold = True

            chartRange = excelWorksheet.Range("A1", "G1")

            With excelWorksheet

                .Cells.Select()

                .Cells.Delete()

                For iC = 0 To colsTotal

                    .Cells(1, iC + 1).Value = DataGridView1.Columns(iC).HeaderText

                    .Cells(1, iC + 1).ColumnWidth = 20

                    .Cells(1, iC + 1).Font.FontStyle = "Bold"

                    .Cells(1, iC + 1).Font.Size = 15

                Next iC

                For I = 0 To rowsTotal

                    For j = 0 To colsTotal

                        .Cells(I + 2, j + 1).value = DataGridView1.Rows(I).Cells(j).Value

                    Next j

                Next I

                '.Cells.ColumnWidth = 15

                .Cells.Select()

                .Cells.EntireColumn.AutoFit()

                .Cells(1, 1).Select()

            End With

        Catch ex As Exception

            'MsgBox("Export Excel Error " & ex.Message)

        Finally

            'RELEASE ALLOACTED RESOURCES

            System.Windows.Forms.Cursor.Current = System.Windows.Forms.Cursors.Default

            xlApp = Nothing

        End Try

End Sub