I've just started a course of Building Technology. I completed reading Lecture 3, but in the task which is: Match the statement with correct answer, I click the statement to match the corresponding answer but it seems the connection doesn't respond. I've tried several times, but no reaction. I clicked on check, and the response I get is: Incorrect! Try again. I've tried several times but to no avail. 

What do I do in order to be able to advance in the course?