Problem With The Attribute Attachdbfile

Hi,
I actualy have a problem with the connection to the databasefile that is stored within the websitetree by visual webdeveloper.
I'm told that  the attribute AttachDbFile  is not understood. How have I to define which database (.mdf-file) should be taken that contains the
tables that are needed in the later processing.
Here the actual code:
Imports Microsoft.VisualBasic
Imports System
Imports System.Data
Imports system.Data.SqlClient
Imports System.Web
Imports System.Xml

Partial Class admin_news
    Inherits System.Web.UI.Page
    Protected Sub DetailsView1_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles DetailsView1.DataBound
        If DetailsView1.CurrentMode = DetailsViewMode.Insert Then
            DirectCast(DetailsView1.FindControl("datumTextbox"), TextBox).Text = Now
        End If
        If DetailsView1.CurrentMode = DetailsViewMode.Edit Then
            DirectCast(DetailsView1.FindControl("datumTextbox"), TextBox).Text = Now
        End If
    End Sub

    'Prozedur wird bei Update ausgeführt

    Public Sub DetailsView1_Update(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.SqlDataSourceCommandEventArgs)
        Dim conn As New SqlConnection("Data Source=.SQLEXPRESS;AttachDbFile=C:Pferdeservice KarleApp_dataPferde.mdf;Integrated Security=True Connection Timeout=30;User Instance=True")
        conn.Open()
        Dim cmd As New SqlCommand()
        Dim cmd1 As New SqlCommand()
        cmd.Connection = conn
        Dim sqlUpdate As String
        Dim sqlUpdate1 As String

        sqlUpdate = "UPDATE News_Kultur set Header = "
        sqlUpdate &= DirectCast(DetailsView1.FindControl("Headers"), TextBox).Text
        sqlUpdate &= "Ueberschrift_D ="
        sqlUpdate &= DirectCast(DetailsView1.FindControl("Ueberschrift_D"), TextBox).Text
        sqlUpdate &= "Ueberschrift_E ="
        sqlUpdate &= DirectCast(DetailsView1.FindControl("Ueberschrift_E"), TextBox).Text
        sqlUpdate &= "Text_D"
        sqlUpdate &= DirectCast(DetailsView1.FindControl("Text_D"), TextBox).Text
        sqlUpdate &= "Text_E"
        sqlUpdate &= DirectCast(DetailsView1.FindControl("Text_E"), TextBox).Text
        sqlUpdate &= "WHERE (((News_Kultur.ID)="
        sqlUpdate &= DirectCast(DetailsView1.FindControl("ArtikelID"), TextBox).Text

        cmd.CommandText = sqlUpdate

        sqlUpdate1 = "UPDATE News set Datum="
        sqlUpdate1 &= DirectCast(DetailsView1.FindControl("datumTextbox"), TextBox).Text
        sqlUpdate1 &= "WHERE ID="
        sqlUpdate1 &= DirectCast(DetailsView1.FindControl("NewsID"), TextBox).Text

        cmd.CommandType = CommandType.Text
        cmd1.CommandType = CommandType.Text
        cmd.ExecuteNonQuery()
        cmd1.ExecuteNonQuery()
        conn.Close()
    End Sub



End Class