Wordpress中sortable_column的问题

I have issue with my sortable columns on a back office Wordpress Table.

No matter which column I click on, the sorting is always done from the date and I don't understand why

With the code I have my page is refreshed after a click with an url like this one "orderby=fundraising&order=asc" but still not working

public function get_sortable_columns()
{
    return array('form-date' => array('form-date', true), 'serie' => array('serie', true), 'fundraising' => array('fundraising', true), 'money_valuation' => array('money_valuation', true));
}

I would like my table to be sorted according to the column I click on

Thanks In advance.