page title and meta description not visible on facebook after posted its url
<p>I have added the below code to page load function to make dynamic page title and meta description in asp.net page. However, not visible on facebook after I post its url.</p>

<p>Any one can help me?<br>
thank you   </p>

<pre><code>        HtmlTitle ht = new HtmlTitle();
        ht.Text = oDt.Rows[0]["Headline"].ToString();
        this.Page.Header.Controls.Add(ht);
        HtmlMeta tag = new HtmlMeta();
        tag.Attributes.Add("property", "og:title");
        tag.Content = oDt.Rows[0]["Headline"].ToString();
        Page.Header.Controls.Add(tag);

        HtmlMeta tag1 = new HtmlMeta();
        tag1.Attributes.Add("property", "og:description");
        tag1.Content = desc;
        Page.Header.Controls.Add(tag1);

        HtmlMeta tagurl = new HtmlMeta();
        tagurl.Attributes.Add("property", "og:url");
        tagurl.Content = HttpContext.Current.Request.Url.AbsoluteUri;
        Page.Header.Controls.Add(tagurl);

        HtmlMeta tagimg = new HtmlMeta();
        tagimg.Attributes.Add("property", "og:img");
        tagimg.Content = "http://www.ethiopianairlines.com/en/graphics/rad/corporate/B787.jpg";
        Page.Header.Controls.Add(tagimg);
</code></pre>
