wp-cron function not running when activating the cron by form submit

Question

I'm activating the cron by a form submit button ( not when plugin is activated ). Thus users have choice to set the cron or not.

But it doesn't trigger the function. The cron is set, but triggering the function. I have loaded/visited the site several time after the cron time is passed to load the cron function.

Here is my code,

function obs_register_menu() {
    add_menu_page( .. 'obs_plugin_fn'... ); // obs_plugin_fn is the function for the plugin page
}

add_action('admin_menu','obs_register_menu'); //add menu

function obs_plugin_fn(){ global $wpdb;

    if(!empty($_POST) && ($_POST['obs_daily_cron_activate']) && !wp_next_scheduled( 'obs_daily_cron' )) { //activate cron on submit
wp_schedule_event(strtotime("now"), 'daily', 'obs_daily_cron');
}

    if(!empty($_POST) && ($_POST['obs_daily_cron_deactivate']) && wp_next_scheduled( 'obs_daily_cron' )) { // de-activate cron on submit
wp_clear_scheduled_hook('obs_daily_cron');
}

    if ( !wp_next_scheduled( 'obs_daily_cron' ) ) {

echo '<form action="" method="post">
<input type="submit" name="obs_daily_cron_activate" class="button button-primary" value="Activate daily cron">
</form>'; // submitting this activate the cron
}
else{
echo '<form action="" method="post">
<input type="submit" name="obs_daily_cron_deactivate" class="button button-primary" value="Deactivate daily cron">
</form>'; // submitting this de-activate the cron
}

// cron schedule

add_action('obs_daily_cron', 'obs_daily_cron_fn');

function obs_daily_cron_fn() {
// do something every day
}

} // end plugin function`

Answer 1

I figured it out.

I had used the function obs_daily_cron_fn() inside the function obs_plugin_fn(). So the function was not triggered untill the plugin page is opened.

Now moving the function obs_daily_cron_fn() out of the function obs_plugin_fn() works perfectly.