Here are a few hints to help you debug possible issues with your theme:

Activate debug in Wordpress
In the file wp-config.php in the root of your WP directory, look for the line:

define('WP_DEBUG', false);

and replace it with:

define('WP_DEBUG', true);
 
If you can't see the line, just add it before the line that reads:

/* That's all, stop editing! Happy blogging. */

Activate debug in the plugin
Go to the WHMCS Bridge options menu and tick the debug option. Debug output will appear in a console on that same page.

Use Firefox and Firebug to look for javascript errors
Firebug is a web development tool that facilitates the debugging, editing, and monitoring of any website's CSS, HTML, DOM, XHR, and JavaScript. It will display JavaScript errors if any on your site. Similar tools are available for Safari, Internet Explorer and Google Chrome.