Not able to display Header Details using cl_salv_table class

Hi Experts,

I have used cl_salv_table to display data for two tables in two containers for containers i have use two cl_gui_docking_container class object.

I have provided Caption and setcaption method in instance still no Header displayed as well tried following method still no Header. please Suggest on this.

DATA: r_dock_container TYPE REF TO cl_gui_docking_container,
r_salv_table TYPE REF TO cl_salv_table,
gv_count TYPE i,
lr_action TYPE REF TO cl_salv_form_action_info.
DATA: lo_header TYPE REF TO cl_salv_form_layout_grid,
lo_h_label TYPE REF TO cl_salv_form_label.

SET PF-STATUS 'STATUS'.
SET TITLEBAR 'TITLEBAR'.
CREATE OBJECT r_dock_container
EXPORTING
side = cl_gui_docking_container=>dock_at_top

EXCEPTIONS
others = 1.

CALL METHOD r_dock_container->set_height
EXPORTING
height = 200.
CALL METHOD cl_salv_table=>factory
EXPORTING
r_container = r_dock_container
IMPORTING
r_salv_table = r_salv_table
CHANGING
t_table = gt_headtab.
*******************Header Details
CREATE OBJECT lo_header
EXPORTING
columns = 1.
lo_h_label = lo_header->create_label( row = 1 column = 1 ).
lo_h_label->set_text( 'Heaer Details' ).

r_salv_table->set_top_of_list( lo_header ).
* ALV Display
r_salv_table->display( ).**
CREATE OBJECT r_dock_container
EXPORTING
side = cl_gui_docking_container=>dock_at_bottom
caption = 'Header Details'
name = 'Header Details'
EXCEPTIONS
others = 1.

CALL METHOD r_dock_container->set_height
EXPORTING
height = 250.

CALL METHOD cl_salv_table=>factory
EXPORTING
r_container = r_dock_container
IMPORTING
r_salv_table = r_salv_table
CHANGING
t_table = gt_itemtab.

r_salv_table->display( ).