Hi. I'm using the walkthrough by MaGtRo. I put in the card used on the night on the murder. Now I'm supposed to be able to turn around and take shreddings out of the shredder and the cat piece from behind the garbage... but my magnifying glass won't even light up over there! What could I have missed? Thanks.

If you are playing as an Amateur sleuth, I would take a look at the task list and see if there is something else that you can try to work on instead for the time being.