Carrie_23 :
I already cleaned my finger,and try again but suddenly cannot notify.
Unfortunately our ability to assist here is going to be severely constrained due to toms' rules regarding circumventing passwords/pins/etc.
Check if there's an OS update, and if not, you may have to reset the phone. Barring that, it's likely to be a hardware issue, at which point you need to contact the manufacturer or other warranty provider for assistance.