call BFA subscribe function from outside Wordpress (to add Subscribe buttons to site)

So I have activated WP functions in my external site by adding the following code at the top of my html:
define('WP_USE_THEMES', false);
require('blog/wp-load.php');

Now I call the following function using this code (not too sure what I'm doing at that point so feel free to let me know if there are security layers to add e.g. check if function exists etc...)

<?php widget_bfa_subscribe(); ?>

And I get:

Warning: Missing argument 1 for widget_bfa_subscribe(), called in /path/mypage.php on line 151 and defined in /path/blog/wp-content/themes/mytheme/functions/bfa_subscribe.php on line 3

Warning: extract() [function.extract]: First argument should be an array in /hpath/blog/wp-content/themes/mytheme/functions/bfa_subscribe.php on line 4

It seems I'm not calling the right function. Yet it does show the icons.

Your help is appreciated.