Ошибка в DataGridView: System.NullReferenceException

    Private Sub Выборка_дата_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        '=== переменная "conn" объявлена публично в Module1 ===
        conn = New OleDbConnection
        conn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=BD_1.accdb;Persist Security Info=False;"
        conn.Open()
        '====================
        Dim s As New OleDbCommand
        s.Connection = conn
        s.CommandText = TextBox1.Text
        Dim ds As New DataSet
        Dim da As New OleDbDataAdapter(s)
        da.Fill(ds, "Прием")
        Grid1.DataSource = ds
        Grid1.DataMember = "Прием"
        Grid1.Columns("Код").Visible = False
        Grid1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells
        '=========================
        Label3.Text = Grid1.Rows.Count
        Me.CancelButton = Button100
    End Sub

       '====================
        Dim s As New OleDbCommand
        s.Connection = conn
        s.CommandText = TextBox1.Text
        Dim ds As New DataSet
        Dim da As New OleDbDataAdapter(s)
        da.Fill(ds, "Прием")
        Grid1.DataSource = ds
        Grid1.DataMember = "Прием"
        Grid1.Columns("Код").Visible = False
        Grid1.Columns("д").Width = 20
        Grid1.Columns("м").Width = 20
        Grid1.Columns("г").Width = 32
        Grid1.Columns("Клиент_ФИО").Width = 200
        Grid1.Columns("Специалист_ФИО").Width = 200
        Grid1.Columns("Время").Width = 50
        'Grid1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells
        '=========================