wp customize don 27t show section

1function panel($wp_customize){
2
3$wp_customize->add_panel('some_panel',array(
4    'title'=>'Panel1',
5    'description'=> 'This is panel Description',
6    'priority'=> 10,
7));
8
9
10$wp_customize->add_section('section',array(
11    'title'=>'section',
12    'priority'=>10,
13    'panel'=>'some_panel',
14));
15
16
17$wp_customize->add_setting('setting_demo',array(
18    'defaule'=>'a',
19));
20
21
22$wp_customize->add_control('contrl_demo',array(
23    'label'=>'Text',
24    'type'=>'text',
25    'section'=>'section',
26    'settings'=>'setting_demo',
27));}   add_action('customize_register','panel');