Error Datagrid

[Capote]

Hola estoy tratando de poder cargar un datagrid , pero al trtar de ejecutar la aplicacion que me muestra el dato me da un error que no entiendo.

Aqui Error:

Additional information: The SelectCommand property has not been initialized before calling 'Fill'.

Código:

 Dim mi_Data_Reader As SqlDataReader
        Dim miComand As SqlCommand
        Dim SqlSelect As String
        Dim dataset As New DataSet
        Dim da As New SqlDataAdapter

        If TextBox1.Text = "" Then
            MessageBox.Show("No dejes Campos Vacios", "Error de Sistema", MessageBoxButtons.OK, MessageBoxIcon.Error)
        Else


            SqlSelect = "execute BuscaDatos " & TextBox1.Text.Trim
            MessageBox.Show(SqlSelect)
            Try
                mi_con = New SqlConnection(cadena_conec)
                miComand = New SqlCommand(SqlSelect, mi_con)
                mi_con.Open()

                mi_Data_Reader = miComand.ExecuteReader


                da.Fill(dataset, "o_pedido")
                DataGrid1.DataSource = dataset
                DataGrid1.DataMember = "o_pedido"


            Catch ex As SqlException
                MessageBox.Show(ex.Message)

            Finally
                If Not mi_Data_Reader Is Nothing AndAlso Not mi_Data_Reader.IsClosed Then mi_Data_Reader.Close()
                If Not miComand Is Nothing Then miComand.Dispose()
                If Not mi_con Is Nothing Then mi_con.Dispose()



            End Try
        End If