errore su treeview

[sabrinef]

errore su treeview

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 [EMAIL="codicepadre=@CodicePadre"]codicepadre=@CodicePadre[/EMAIL] 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..........