Thank you for using Auto ThickBox Plus.
Did you see the plugin FAQ page?
Auto ThickBox Plus does not work
Then you use Head JS and W3 Total Cache.
If you use Head JS, select [General - ThickBox Resources - Footer] option.
Uncaught TypeError: Object [object Object] has no method 'placeholder' (59669f27.44ae03.js:1004)
Uncaught ReferenceError: tb_options is not defined (snapshot-reflexiones-reflections-opening-at-cafe-con-leche:252)
Uncaught TypeError: object is not a function (59669f27.44ae03.js:12)
Uncaught TypeError: Cannot read property 'client' of undefined (/wp-content/plugins/wpng-calendar/js/functions.js?ver=0.85:49)
And you use wpng-calendar but it loads jQuery and ThickBox scripts without using WordPress function. So there are jQuery and ThickBox conflicts in your site. You need to modify wpng-calendar if you want to use it.