protected void bt_submit_Click(object sender, EventArgs e)
        {
            confirm.Visible = false;
            error.Visible   = false;

            Member m = Member.GetCurrentMember();

            int pId = 0;

            if (!string.IsNullOrEmpty(Request.QueryString["id"]) && int.TryParse(Request.QueryString["id"], out pId) && umbraco.library.IsLoggedOn())
            {
                Document d = new Document(pId);

                if ((int)d.getProperty("owner").Value == m.Id)
                {
                    Member c = Member.GetMemberFromLoginName(tb_email.Text);

                    if (c != null && c.Id != m.Id)
                    {
                        //member found

                        ProjectContributor pc = new ProjectContributor(d.Id, c.Id);
                        pc.Add();

                        confirm.Visible = true;
                        tb_email.Text   = "";
                    }
                    else
                    {
                        //member not found
                        error.Visible = true;
                    }
                }
            }
        }