Hi,
I did check your website. The widget does come up on the page, but it does not have any content and so its all blank.
The reason I can think of there must be something wrong with the widget code.
Can you please check again if you are putting up the correct code.
Alternatively you can use this plugin - https://wordpress.org/plugins/easy-twitter-feed-widget/
I would suggest you use this plugin.
Let me know if you need more help.
Shreyans