problema con TreeView

[s.ef]

Ciao

ho una pagina master con un controllo treeview che però mi dà errore......mentre se lo eseguo in pagina aspx normale con VB associato finziona tranquillamente........

vi posto il codice:

pagina VB:

Partial Public Class template

    Inherits MasterPage


    Dim temp As String
    Dim cont As Integer

    Protected Sub Menu_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not IsPostBack Then
            Dim nodo As New TreeNode
            NodoPrincipale(nodo, 1)
            TreeView1.Nodes.Add(nodo)


            nodo.Text = "MENU"


            'nodo.Target = ""
            TreeView1.CollapseAll()
            TreeView1.Nodes(0).Expand()

            ' MsgBox.Show(Me.lbCodiceOrdine.ID.ToString(), Page)
        End If
    End Sub
    Private Sub NodoPrincipale(ByVal nodo As TreeNode, ByVal codicePadre As Integer)
        Try
            Dim da As New OleDbDataAdapter
            Dim ds As New DataSet
            Dim strsql As String = "SELECT Collegamento, Titolo,codice,url,TARGET,images FROM MENU Where codicepadre='" + CStr(codicePadre) + "' ORDER BY Codice"
            da = New OleDbDataAdapter(strsql, objdb)
            da.Fill(ds, "menu")
            'Dim Cmd As New OleDbCommand("SELECT Collegamento, Titolo,codice,url,TARGET,images FROM MENU Where codicepadre=@CodicePadre ORDER BY Codice", objdb)
            'Cmd.CommandType = CommandType.Text
            Dim dtable As DataTable = ds.Tables("menu")
            'Dim currRows() As DataRow = dtable.Select(Nothing, Nothing, DataViewRowState.CurrentRows)
           
            For Each rowTipo As DataRow In dtable.Select(Nothing, Nothing, DataViewRowState.CurrentRows)
                Dim nodeTipo As System.Web.UI.WebControls.TreeNode = New System.Web.UI.WebControls.TreeNode
                If IsDBNull((rowTipo("Url"))) Then
                    nodeTipo.NavigateUrl = ""
                Else
                    nodeTipo.NavigateUrl = rowTipo("Url")
                End If

                If IsDBNull((rowTipo("TARGET"))) Then
                    nodeTipo.Target = "_self"
                Else
                    nodeTipo.Target = rowTipo("TARGET")
                End If

                If IsDBNull((rowTipo("images"))) Then
                    nodeTipo.ImageUrl = ""
                Else
                    nodeTipo.ImageUrl = rowTipo("images")
                End If

                nodeTipo.Text = rowTipo("Titolo")


                If IsDBNull((rowTipo("collegamento"))) Then
                    temp = 0 + rowTipo("codice")
                Else
                    temp = rowTipo("collegamento")
                End If

                nodeTipo.Value = temp
                nodeTipo.ToolTip = rowTipo("codice")
                nodo.ChildNodes.Add(nodeTipo)

                If Not IsDBNull((rowTipo("collegamento"))) Then
                    NodoPrincipale(nodeTipo, temp)
                End If

            Next

        Catch ex As Exception

        End Try
    End Sub
    

   
    Protected Sub TreeView1_SelectedNodeChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TreeView1.SelectedNodeChanged

        


        If TreeView1.SelectedNode.Expanded.ToString() = True Then
            TreeView1.SelectedNode.Collapse()
        Else
            TreeView1.SelectedNode.Expand()

                   End If
    End Sub
End Class

pagina asp con controllo treeview

<table style="width: 208px" border="0">
            <tr>
                <td style="width: 204px">
     <asp:TreeView ID="TreeView1"  runat="server" Height="550px" Width="152px" 
                Font-Size="12pt" 
            style="font-family: 'Times New Roman', Times, serif;font-size: small" 
                ImageSet="Simple" OnSelectedNodeChanged="TreeView1_SelectedNodeChanged" BackColor="GhostWhite" Font-Names="Arial" Font-Strikeout="False" ForeColor="DimGray">
            <selectednodestyle Font-Names="Arial" Font-Size="12pt" ForeColor="DimGray" />
         <ParentNodeStyle Font-Names="Arial" Font-Underline="True" ForeColor="DimGray" />
         <HoverNodeStyle BackColor="White" />
         <NodeStyle BackColor="Transparent" />
        </asp:TreeView>   
                </td>
               
            </tr>
          
           
        </table>

errore che mi viene

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. 

Compiler Error Message: BC30456: 'TreeView1_SelectedNodeChanged' is not a member of 'ASP.template_master'.

Line 47:             <tr>
Line 48:                 <td style="width: 204px">
Line 49:      <asp:TreeView ID="TreeView1"  runat="server" Height="550px" Width="152px" 
Line 50:                 Font-Size="12pt" 
Line 51:             style="font-family: 'Times New Roman', Times, serif;font-size: small"

vi prego aiutatemi..........