// initializers
        protected void Page_Load(object sender, EventArgs e)
        {
            NinaSubscriptionsMaster master = this.Master as NinaSubscriptionsMaster;
            master.setHeaderTitle(settingsHelper.get("title_beheer_cursussen"));

            userProfile user = master.getLoggedInUserProfile();
            if (user == null || user.isAdmin == false) { Response.Redirect("~/Pages/Public/bekijkAanbod.aspx"); };

            crud crud = new crud();
            locations = crud.getAllLocations();
            courseTypes = crud.getAllCourseTypes();

            if (IsPostBack) {
                try {
                    selectedCourseType = crud.selectCourseType(Convert.ToInt32(ddNewCourseType.SelectedValue));
                    selectedLocation = crud.selectLocation(Convert.ToInt32(ddNewLocation.SelectedValue));
                } catch {
                    // objecten blijven null, hierop wordt later gecontroleerd
                }
            } else {
                fillCoursesList(crud);
            }
        }