Cl_gui_alv_tree no child nodes after registering event

Question

Hey guys,
I have an uncommon problem with cl_gui_alv_tree.
My tree has 2 layers, Root and child. Both of them have layout-class  cl_gui_column_tree=>item_class_checkbox.
Everithing works fine! (without_events.jpg)
But if I register event "checkbox_change" with method SET_REGISTERED_EVENTS the childnodes disapear! (with_events.jpg)
Does anyone know a solution?
here's some code:
data; gr_alv_0200 type ref to cl_gui_alv_tree.
METHOD init_dynpro_0200.
     DATA: ls_hierarchy_header TYPE treev_hhdr.
     IF gr_cont_0200 IS INITIAL.
       CREATE OBJECT gr_cont_0200
         EXPORTING
           container_name              = 'CC200'
         EXCEPTIONS
           cntl_error                  = 1
           cntl_system_error           = 2
           create_error                = 3
           lifetime_error              = 4
           lifetime_dynpro_dynpro_link = 5
           OTHERS                      = 6.
       IF sy-subrc <> 0.
         MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
                    WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
       ENDIF.
     ENDIF.
     IF gr_alv_0200 IS INITIAL.
       CREATE OBJECT gr_alv_0200
         EXPORTING
*         lifetime                    =
           parent                      = gr_cont_0200
           node_selection_mode         = cl_gui_column_tree=>node_sel_mode_single
           item_selection              = 'X'
           no_toolbar                  = 'X'
           no_html_header              = 'X'
         EXCEPTIONS
           cntl_error                  = 1
           cntl_system_error           = 2
           create_error                = 3
           lifetime_error              = 4
           illegal_node_selection_mode = 5
           failed                      = 6
           illegal_column_name         = 7
           OTHERS                      = 8.
       CHECK sy-subrc EQ 0.
       ls_hierarchy_header-heading = 'Hierarchy Header'.     "#EC NOTEXT
       ls_hierarchy_header-tooltip =
                              'This is the Hierarchy Header !'. "#EC NOTEXT
       ls_hierarchy_header-width = 100.
       ls_hierarchy_header-width_pix = ''.
        tree_create_fcat( ).
       CALL METHOD gr_alv_0200->set_table_for_first_display
         EXPORTING
           is_hierarchy_header = ls_hierarchy_header
           i_background_id     = 'ALV_BACKGROUND'
         CHANGING
           it_outtab           = gt_treenodes
           it_fieldcatalog     = gt_fcat_0200.
       DATA: lt_events TYPE cntl_simple_events,
                 ls_event LIKE LINE OF lt_events.
       ls_event-eventid = cl_gui_column_tree=>eventid_checkbox_change.
       APPEND ls_event TO lt_events.
       CALL METHOD gr_alv_0200->set_registered_events
         EXPORTING
           events                    = lt_events
         EXCEPTIONS
           cntl_error                = 1
           cntl_system_error         = 2
           illegal_event_combination = 3.
       SET HANDLER me->on_tree_checkbox_change FOR gr_alv_0200.
     ENDIF.
   ENDMETHOD.
METHOD tree_add_node.
     DATA: ls_node_text TYPE lvc_value.
* set item-layout
     DATA: lt_item_layout TYPE lvc_t_layi,
           ls_item_layout TYPE lvc_s_layi.
     ls_item_layout-fieldname = gr_alv_0200->c_hierarchy_column_name.
     ls_item_layout-style   = cl_gui_column_tree=>style_intensifd_critical.
     ls_item_layout-class   = cl_gui_column_tree=>item_class_checkbox.
     ls_item_layout-editable = 'X'.
     APPEND ls_item_layout TO lt_item_layout.
* add node
     ls_node_text =  is_data-name.
     DATA: ls_node TYPE lvc_s_layn.
     ls_node-n_image   = space.
     ls_node-exp_image = space.
     CALL METHOD gr_alv_0200->add_node
       EXPORTING
         i_relat_node_key = iv_parent
         i_relationship   = cl_gui_column_tree=>relat_last_child
         i_node_text      = ls_node_text
         is_outtab_line   = is_data
         is_node_layout   = ls_node
        it_item_layout   = lt_item_layout
       IMPORTING
         e_new_node_key   = ev_node_id.
   ENDMETHOD.
in my current class I've method on_tree_checkbox_change to handle the event. If the event is registered, the method gets called.

Answer 1

Solved by my own:
I had to implement method get_registered_events( ), append the new event to the table and call set_registered_events( ).
The table from get_registered_events( ) is already filled with events.