FindControlEx

Function FindControlEx(ByVal Parent As System.Web.UI.Control, ByVal ID As String) As System.Web.UI.Control
        Dim oCtrl As System.Web.UI.Control = Nothing
        Dim oChildCtrl As System.Web.UI.Control = Nothing

        '先使用 FindControl 去尋找指定的子控制項  
        oCtrl = Parent.FindControl(ID)

        '若尋找不到則往下層遞迴方式去尋找() 
        If oCtrl Is Nothing Then
            For Each oChildCtrl In Parent.Controls
                '以遞迴方式呼叫原函式 
                oCtrl = FindControlEx(oChildCtrl, ID)
                '若有尋找到指定控制項則離開迴圈 
                If oCtrl IsNot Nothing Then Exit For
            Next
        End If
        Return oCtrl
End Function

Source