Action hook

Hello there,

First of all, thank you for this great plugin.

I am looking for a way to execute a custom function when someone click on the like button using add_action() but I cannot figure out how to.

I tried :
add_action(‘wp_ajax_postratings’, ‘custom_function’);
add_action(‘wp_ajax_nopriv_postratings’, ‘custom_function’);
add_action( ‘process_ratings’, ‘bp_like_activity_add’, 99, 2 );

But it does not work.

I would really appreciate some support.

Thank you