VB.NET How to merge cell in excel

Imports Microsoft.Office.Core
Imports Microsoft.Office.Interop

Private Sub MergeCell()
        Dim xlApp As New Excel.Application
        Try
            'Open file
            Dim xlBook As Excel.Workbook = xlApp.Workbooks.Open("Excel file path")
            'Get the sheet
            Dim xlSheet As Excel.Worksheet = xlBook.Worksheets("Sheet1")
            With xlSheet
                '(1)From A6 to A8 Cell merge
                .Range("A6:A8").Merge()

                 '(2)From D6 to D8 Cell merge

                .Range("D6:D8").Merge()

                '(3)From C6 to C8 Cell merge

                .Range(.Cells(6, 3), .Cells(8, 3)).Merge()
            End With
        Catch ex As Exception
           Console.WriteLine(ex.Message)
        End Try
    End Sub