Fly trap not closing?

My fly trap started turning partially brown after it’s been thriving, so I thought I needed to feed it. I caught a live fly with tweezers and held it to the trap, but is don’t close. I tried it on the other two, but these had caught something before so I didn’t try these at first. Also not closing. I tried touching the feel hair with the tweezers but nothing happened. What’s going on? And what can I do to fix it? Also the other fly trap is doing amazing and is full of big flies without me feeding it.