(FaceBook OAuthException - #200) Unpublished posts must be posted to a page as the

I have written below function to post single Photo to FB page. But getting error saying "(OAuthException - #200) (#200) Unpublished posts must be posted to a page as the page itself."

private void postToFBPage()
{
    string app_id = ConfigurationManager.AppSettings["FBAppKey"];
    string app_secret = ConfigurationManager.AppSettings["FBSecretKey"];
    string scope = ConfigurationManager.AppSettings["FBPermission"];
    string access_token;

    if (Session["access_token"] == null)
        access_token = getAccessToken();
    else
        access_token = Session["access_token"].ToString();

        var client = new FacebookClient(access_token);
        List<string> imgs = (List<string>)Session["local_processedImgs"];

        DateTime dt=new DateTime(Convert.ToInt32(ddlYear.SelectedValue)
                                ,Convert.ToInt32(ddlMonth.SelectedValue)
                                ,Convert.ToInt32(ddlDate.SelectedValue)
                                ,Convert.ToInt32(ddlHour.SelectedValue)
                                ,Convert.ToInt32(ddlMin.SelectedValue)
                                ,0);

        double UTC = Facebook.DateTimeConvertor.ToUnixTime(dt);

        dynamic post = null;
        dynamic parameters = new ExpandoObject();
        parameters.source = new FacebookMediaObject
        {
            ContentType = "image/" + Path.GetExtension(imgs[0]),
            FileName = imgs[0]
        }.SetValue(File.ReadAllBytes(imgs[0]));
        parameters.message = CKEditor1.Text;
        parameters.scheduled_publish_time = UTC;
        parameters.published = false;
        parameters.scope = scope;

        try
        {
            post = client.Post("/" + ddlFBPage.SelectedValue + "/photos" , parameters);
        }
        catch (Exception ex)
        {
            //error
        }
}

Please help me on this.

--

Regards

Deepak Rai