Why does the DISC test say I haven't answered all questions when I have?

Every question in the DISC test consists of four statements, of which you should indicate the one you like least and the one you like most. Please make sure you've selected one thumb up (green) and one thumb down (red) for every four statements. If you find it hard to choose, please remember a red thumb doesn't mean you don't like the statement, just that it's the statement least like you.

Below: an example of a correctly filled out DISC block, with one red and one green thumb