i want to show records from other tables but this error occurs

Sub fillorderdetail()

        Dim adpt As New SqlDataAdapter("select * from orderdetail", conn)
        Dim ds As New DataSet
        adpt.Fill(ds, "orderdetail")
        DataGridView2.DataSource = ds.Tables("orderdetail")
    End Sub

There will be something wrong with the connection string for the connection object. Where and how are you specifying the connection object?