custom action button doesn't shown

Hello, new GC user here~

I just learn how to use Grocery Crud a little while ago (and in programming as well). So... I tried to create a custom action button for the table using the add_action() function, yet the button doesn't appear in the action column of the table and yet the system doesn't return any error fatal errors.

Below is the said code;

public function on_progress()

{

$this->grocery_crud->set_model('Custom_query_model');

$this->grocery_crud->set_table('complaints');

$this->grocery_crud->set_theme('flexigrid');

$this->grocery_crud->basic_model->set_query_str("SELECT complaints.*, category.category_name,facilities_services. fs_name, trade.trade_name,

problem_type.problem_type,level.level, users.name,contractor.name

FROM complaints

LEFT JOIN category ON complaints.category_id = category.id

LEFT JOIN facilities_services ON complaints.fs_id = facilities_services.id

LEFT JOIN users ON complaints.report_by = users.id

LEFT JOIN trade ON complaints.trade_id = trade.id

LEFT JOIN problem_type ON complaints.problem_type_id = problem_type.id

LEFT JOIN level ON complaints.level_id = level.id

LEFT JOIN contractor ON complaints.contractor_id = contractor.id

WHERE category.id = facilities_services.category_id

AND facilities_services.id = problem_type.fs_id AND

complaints.report_by = users.id

");

$this->grocery_crud->columns('id','category_name','fs_name', 'trade_name',

'problem_type', 'level', 'users.name', 'event_datetime',

'event_completed', 'contractor.name','work_status',

'complaint_photo','completion_photo','overall_status'

);

$this->grocery_crud->display_as('id','Complaint Id');

$this->grocery_crud->display_as('category_name', 'Category');

$this->grocery_crud->display_as('fs_name','Facilities/Services');

$this->grocery_crud->display_as('trade_name','Problem Category');

$this->grocery_crud->display_as('problem_type','Problem Type');

$this->grocery_crud->display_as('level', 'Level');

$this->grocery_crud->display_as('users.name','Report By');

$this->grocery_crud->display_as('contractor.name','Craftsmen');

$this->grocery_crud->add_action('this','','','',array($this,'assign_Craftsmen'));

$this->grocery_crud->callback_column('complaint_photo', array($this,'show_ComplaintImage'));

$this->grocery_crud->callback_column('completion_photo', array($this,'show_CompleteImage'));

function show_ComplaintImage($value)

{

return "<img src='".$value."' width='100px'>";

}

function show_CompleteImage($value)

{

return "<img src='".$value."' width='100px'>";

}

function assign_Craftsmen($primary_key, $row)

{

}

$output = $this->grocery_crud->render();

$this->load->view('templates/header');

$this->load->view('templates/header_grocery_crud');

$this->load->view('templates/header_menu');

$this->load->view('forms/updateForm', $output);

$this->load->view('templates/footer_grocery_crud');

$this->load->view('templates/footer');

}

Thanks a lot~

custom action button doesn't shown

z.kerry