Meta tags displaying null in ASP.Net

Hi

As per the article Adding Meta tags to Master Page and ASPX Child Content Pages in ASP.Net.

I have developed a following code for add Meta tags dynamically in each product pages.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Dim dtMeta As DataTable = GetData()
 
    ''Add Page Title.
    Me.Page.Title = dtMeta.Rows(0)("ItemName").ToString()
 
    'Add Keywords Meta Tag.
    Dim keywords As New HtmlMeta()
    keywords.HttpEquiv = "keywords"
    keywords.Name = "keywords"
    keywords.Content = dtMeta.Rows(0)("MetaTagKeywords").ToString()
    Me.Page.Header.Controls.Add(keywords)
 
    'Add Description Meta Tag.
    Dim description As New HtmlMeta()
    description.HttpEquiv = "description"
    description.Name = "description"
    description.Content = dtMeta.Rows(0)("MetaTagDescription").ToString()
    Me.Page.Header.Controls.Add(description)
 
    If Not IsPostBack Then
        If Page.RouteData.Values("ProductName") Is Nothing Then
            Response.Redirect(ResolveUrl("~/products"))
        Else
            BindData_ExpProducts_ItemName_Web()
            BindData_Repeater1()
        End If
    End If
End Sub
Private Function GetData() As DataTable
    Using cmd As New SqlCommand("ExpProducts_ItemName_Web")
        cmd.Connection = constrWeb
        cmd.CommandType = CommandType.StoredProcedure
 
        cmd.Parameters.Add("@ProductName", SqlDbType.NVarChar, 100).Value = Page.RouteData.Values("ProductName")
 
        Using sda As New SqlDataAdapter()
            cmd.Connection = constrWeb
            sda.SelectCommand = cmd
            Dim dt As New DataTable()
            sda.Fill(dt)
            Return dt
        End Using
    End Using
End Function

Page title display but, meta tag not change.  

Thanking you 

samsmuthu