Problem creating cron job wordpress

Here’s the minified reference I use for setting up WordPress cron, which is all from wp_schedule_event() and cron_schedules:

Setup Cron

// SETUP CRON
add_action('wp', 'myplugin_schedule_cron');
function myplugin_schedule_cron() {
  if ( !wp_next_scheduled( 'myplugin_cron' ) )
    wp_schedule_event(time(), 'daily', 'myplugin_cron');
}

Cron Function

// the CRON hook for firing function
add_action('myplugin_cron', 'myplugin_cron_function');
#add_action('wp_head', 'myplugin_cron_function'); //test on page load

// the actual function
function myplugin_cron_function() {
    // see if fires via email notification
    wp_mail('[email protected]','Cron Worked', date('r'));
}

Custom Cron Time Interval

if WordPress’s default hourly, daily, aren’t enough, you can create your own.

// CUSTOM TIME INTERVAL
add_filter('cron_schedules', 'myplugin_cron_add_intervals');
function myplugin_cron_add_intervals( $schedules ) {
  $schedules['customTime'] = array(
    'interval' => 30,
    'display' => __('Every 30sec')
  );
  return $schedules;
}

replacing daily in wp_schedule_event() with customTime

Viewing Crons

You can also view your cron via a gui with a plugin: https://wordpress.org/plugins/search/cron+view/