why ServerValidate will not handled?

i added dynamically below controls in below class and defined controls properties in PreRender event, and also defined ServerValidate event of CustomValidator, but this event will not handled.


anyone can help me?


class code


Imports System.Text
Imports System.Web
Imports System.Web.UI.WebControls
Imports System.Web.UI


Public Class Intergrated
    Inherits UserControl

    'Private Sub BuildHtml()
    '    Dim text As String = If(Context.Request.QueryString("q") <> Nothing, HttpUtility.HtmlEncode(Context.Request.QueryString("q")), BlogSettings.Instance.SearchDefaultText)
    '    Dim sb As New StringBuilder()
    '    sb.AppendLine("<div id=""searchbox"">")
   ...