How to post to Facebook Group using Facebook Sdk C#

I am using Facebook Sdk C# To develop a desktop program for publication posts in Facebook groups. The software will publish only to 5 groups , if possible to any correct my problem

this Method i use

My separate Class File

public static string UploadPost(string groupid, string intTitle, string inMessage, string inLinkCaption, string inLinkUrl = "", string inLinkDescription = "", string inLinkUrlPicture = "")
    {
        object obj;
        Facebook.JsonObject jsonObj;
        FacebookClient client;
        string access_token = AppSettings.Default.AccessToken.ToString();

        client = new FacebookClient(access_token);

        var args = new Dictionary<string, object>();

        args["message"] = inMessage;
        args["caption"] = inLinkCaption;
        args["description"] = inLinkDescription;
        args["name"] = intTitle;
        args["picture"] = inLinkUrlPicture;
        args["link"] = inLinkUrl;

        if ((obj = client.Post("/" + groupid + "/feed", args)) != null)
        {
            if ((jsonObj = obj as Facebook.JsonObject) != null)
            {

                if (jsonObj.Count > 1)
                    return jsonObj[1].ToString();
            }
        }

        return string.Empty;
    }

    internal static bool UploadPost(string p1, string p2)
    {
        throw new NotImplementedException();
    }

    public static string link { get; set; }
}

}

And this my Post Button

        private void btnPost_Click(object sender, EventArgs e)
    {

        if (IsLogin != true)
        {

            bntLogin.Hide();
            btnLogout.Show();
            frmLogin frm = new frmLogin();
            frm.ShowDialog();

            System.Threading.Thread.Sleep(15000);
            for (int i = 0; i < lstgroups.Items.Count; i++)
            {



                //هنا الفاصل الزمني
                System.Threading.Thread.Sleep(15000);
                // هنا كود الفصل

                if (Class1.UploadPost(lstgroupsbox.Items[i].ToString(),"", txtStatus.Text,"", txtLink.Text,"", txtImagePath.Text) == string.Empety)
                    lblshow.Text = "Sent To " + lstgroups.Items[i].Text;
                {
                    //foreach (var item in lstgroups.Items)
                    //{
                    //    if (Class1.UploadPost(item.ToString(), "", txtStatus.Text, "", 2, "", txtImagePath.Text) != string.Empty)
                    //        MessageBox.Show("Post Has Been Sent");
                    //}

                }
            }
        }
    }