มีปัญหาเกี่ยวกับการติดต่อฐานข้อมูล SQL Server ด้วย VB 2008 ค่ะ

Imports System.Data
Imports System.Data.SqlClient

Public Class Form1

    Dim Conn As New SqlConnection   'ประกาศตัวแปรออบเจ็กต์ Connection
    Dim da As SqlDataAdapter
    Dim ds As DataSet

    Private Sub btnSQL_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSQL.Click

        Dim strConn As String

        strConn = "Data Source=.\SQLEXPRESS;AttachDbFilename='C:\Program Files\" & _
                "Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\Data\db_stp.mdf';" & _
                "Integrated Security=True;Connect Timeout=30;User Instance=True"

        With Conn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = strConn
            .Open()
        End With

        Try
            Dim strSQL As String

            strSQL = txtSQL.Text

            ds.Clear()
            da = New SqlDataAdapter(strSQL, Conn)
            da.Fill(ds, "MyData")

            dgvSQL.DataSource = ds.Tables("myData")
            Conn.Close()
        Catch ex As Exception
            MessageBox.Show(ex.ToString, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try
    End Sub
End Class