Sidebar link isn't working from within a post.

Hello!

I’ve placed a text widget on the sidebar that includes a gif, which links to a specific post on my blog when clicked.

This all works fine if on the home page – if you click the gif, you get taken to the appropriate page. But, when you are viewing a post, and then click the gif in the sidebar, the link will not work and you’re taken to a page with an error message.

I’ve googled to see if this was a general wordpress fault I needed to fix but can’t find anything on it, so assumed it’s something to do with the theme?

If you can let me know how to fix this, that would be great!

url is http://www.thevisualbloq.com – scroll down to see the gif in the sidebar