Visual Basic

Private Sub OpenFolder_Click(sender As Object, e As EventArgs) Handles OpenFolder.Click
       FolderBrowserDialog1.ShowDialog()
       FolderPath.Text = FolderBrowserDialog1.SelectedPath.ToString()
       loadfiles()
   End Sub
   Private Sub loadfiles()
       Dim filepath As String() = Directory.GetFiles(FolderPath.Text)
       Dim dt As DataTable = New DataTable
       dt.Columns.Add("Product")
       dt.Columns.Add("Serial No")
       dt.Columns.Add("Extension")
       dt.Columns.Add("Size")
       dt.Columns.Add("Creation Time")
       For item As Integer = 0 To filepath.Length - 1
           Dim file As New FileInfo(filepath(item))
           Dim dr As DataRow = dt.NewRow()
           dr(0) = file.Name.Split.Distinct
           dr(1) = file.Name
           dr(2) = file.Extension
           dr(3) = file.Length
           dr(4) = file.LastWriteTime
           dt.Rows.Add(dr)
       Next
       DataGridView1.DataSource = dt

   End Sub

me.datagridview_1.rows.add("ColumnName",stringvalue)
or 
me.datagridview_1.rows.add(string1, string2,string3)

The above does not add an additional line
If I load a form and populate the obj the above is fine
I need to add an extra line(s) manually, say either with textbox controls or other vars