apply filters on wordpress get_posts

I wish to limit the get_posts() result by dates
i tried using the following but it is not working for me…

can anyone tell me if im doing this correctly ? and why is not performing as expected ?

add_filter( 'posts_where', 'filter_dates_between' );

$args=array(
        'post_type'=>'log',
        'suppress_filters' => false,
        'post_status'=>'private',
        'numberposts'=> -1,
        'meta_key'=>'_wpcf_belongs_agent_id','meta_value'=>$agentId);

$logs=get_posts($args);

remove_filter( 'posts_where', 'filter_dates_between' );

here is the filter function

function filter_dates_between( $where =''  ) {
                global $dateFrom,$dateTo,$wpdb;

                $where .= $wpdb->prepare( " AND post_date >= %s", $dateFrom );
                $where .= $wpdb->prepare( " AND post_date <= %s", $dateTo );

                return $where;
    }