Meta Tag populated from database not showing on page source ASP.Net

HI

I populate mete tag from database according to this thread

http://www.aspforums.net/Threads/143820/Populate-SEO-Keywords-and-Description-meta-tags-from-SQL-Server-Database/

in store.aspx page i have this behinde code

 protected void Page_Load(object sender, EventArgs e)
    {
 


       string data = Server.UrlDecode(Request.QueryString["BehCode"]);

        
            
        
        SqlCommand _cmd = new SqlCommand("storeInfo", _cn);
        _cmd.CommandType = CommandType.StoredProcedure;
        _cmd.Parameters.AddWithValue("@BehCode",data);
        _cn.Open();
        SqlDataReader _dr = _cmd.ExecuteReader();
      
        while (_dr.Read())
        {



            HtmlMeta htmlMeta;
            string keyword = _dr["Keyword"].ToString();
            htmlMeta = new HtmlMeta();
            htmlMeta.HttpEquiv = "keywords";
            htmlMeta.Content = keyword;
            this.Page.Header.Controls.Add(htmlMeta);


            Lblbehcode.Text = _dr["Name"].ToString();
            Image1.ImageUrl = "~/image/behcode/" + _dr["Image_Behcode"].ToString();

           
            


        }

and StoreProcedure

ALTER procedure [dbo].[storeInfo]
@BehCode nvarchar(10)
as
begin
select Name,Image_Behcode,Tell,Description,address,about,(Keyword1+','+Keyword2+','+Keyword3+','+Keyword4) as keyword
from House_Info
where BehCode=@BehCode
end

here instesd of 

stringkeyword = _dr[0].ToString();

I put

string keyword = _dr["Keyword"].ToString();

but when i run website and see viewsource it doesn't show any thing in meta tag

what can i do to solve this problem?

Regards