I decoded the eye chart and got
Sous Lorraine 4154
I thought I was supposed to
press the numbers on the cross, but it won't let me! I have already gotten under the moulin, but need a key to get past. That key is the only thing left I need to solve the mystery. I have played this game many times before.

EDIT: I had decoded the message outside the game on my own sheet of paper. I had to solve it on the piece of paper that Nancy had. Now what I need to do is unlocked!