End thumbnail not showing up

Hi there,

I’m using the Grid Theme Responsive, and I’m having a problem with the accommodation of the posts. Whereas there should be 4 columns, my first row fails to show the 4th post to complete the row.

My site is not live, so if you’d like to help I’d have to get you credentials, but here is a picture of what I’m working with.

Note the empty 4th post. For some reason, it doesn’t fill that spot it just continues on the bottom row.

https://oi67.tinypic.com/16c5g5s.jpg