Modifier ID asp dans une class

<asp:Label ID="lblCreer" runat="server" Text=""></asp:Label>

ModifControl(Me)

Public Sub ModifControl(page As System.Web.UI.Page)
Label lblCreer = CType(page.FindControl("lblCreer"),Label)
' la suite ...

lblCreer.Text = "toto"
End Sub

if lblcreer is nothing then
 return false
end if
lblcreer.text = "test"

<asp:Content ID="Content1" ContentPlaceHolderID="Main" runat="Server">
<asp:Label ID="LbComp" runat="server" Text=""></asp:Label></div>
</asp:Content>

Page.FindControl("Content1")

Dim lbl_sent As New Label
lbl_sent = CType(Page.FindControl("LbComp"), Label)
If lbl_sent Is Nothing Then
  Return False
End If
lbl_sent.Text = "test"

Try
   Dim Conetent1 As ContentPlaceHolder = DirectCast(Page.FindControl("Content1"), ContentPlaceHolder)
   Dim lbl_sent As Label = DirectCast(Conetent1.FindControl("LbComp"), Label)
   lbl_sent.Text = "test"
Catch Ex As Exception
   '
End Try