Flexslider does not show slides in pop-up overlay

[melindaSA]

I have flexslider in a pop-up overlay and the slides do not show unless I refresh.
jQuery(document).ready(function($){ $('.flexslider').flexslider({ animation: "fade", slideshow: false, start: function(slider){ $('body').removeClass('loading'); } }); });
How can I force flexslider to initialize only when the overlay pop-up is opened?

Here is the page: http://tracker.winnowhost.com/ click on Accounting button under Features. For now I am doing a onClick="window.location.reload()" to refresh so that the slider works. If I do not refresh then there is an empty space where the slider should be, but the left and right arrows do show.

Any help!!
Thanks!