Hello!
I don't think you're doing anything wrong. You do have to be fairly precise (as another user has posted) with your letter placement. Sometimes, even if I have the right area, if my number isn't half-covering the specific spot, it won't register. It can be a little frustrating when you need to open your phone fast, but I'm sure you'll get used to it! And then unlocking it will be much faster. Luckily, you can still get into your phone if you can't hit the right spot five times - this has happened to me, lol.
Don't worry!
