Im getting an error in the console when i click the button. The modal begins to open because the overlay is being shown.
TypeError: f.curCSS is not a function
After a google search i found this http://wordpress.org/support/topic/typeerror-ccurcss-is-not-a-function?replies=4
If you upgraded your jquery version you may need to also update your jquery ui.
The modal is opening but uses background color animations and we include a color animation plugin but since your theme is loading jquery-ui after our animation js file its bg-color animation overrides our functions, because of this your options are to either upgrade jquery-ui or remove it if your not using it.
Hope this helps.