[NDS] Lego Harry Potter Years 5-7 (U) Lumos Help!

Basically, I keep trying to cast 'Lumos' on the Devil's Snare, but it's not working. I'm on the Legilimancy bit, where you're at King Cross Station. I keep holding down the stylus to cast Lumos, and the circle appears on the top screen, but when I hover over the Devil's Snare, I can't cast it at it.I've tried on different levels as well, but I can't cast any spells at the Devil's Snare.Any help or answers most appreciated!Thanks!

You have to select lumos, then you just press A and your want will light-up. Then you walk closer to the devils snare and it will disappear. press A again and Lumos will disappear.

Okay, thank you so much! I was really stuck - I thought my game was broken.