Posted by Shane
When you are writing a plugin that uses Ajax in the front end, you must use:
add_action( 'wp_ajax_nopriv_<ACTION NAME>', <YOUR FUNCTION> );
add_action( 'wp_ajax_<ACTION NAME>', <YOUR FUNCTION> );
… is only for logged in users. So if you have a plugin that operates no matter which way users interface with the plugin, you must provide both action calls to make sure it all gets processed. Helpful tip.
Will be back shortly…