If you go down the left hand side, then go to the right and then up, then right, then up, then left back to where the validation point is, you should get it. Just remember that if it says 'Failure', be sure to click on it again and click on the 'reset' (not sure just what it says, but the other one from 'validate') and then try again. I found that you couldn't explore if you wanted to validate it... then you can!
Hope this helps.