UMI Touch- Fingerprint Problem

OzgunUz

Hi everyone,

I bougt an UMI Touch and I received today. But I can not use fingerprint with my thumb (finger). I can unlock screen lock with other fingers. But I can not unlock with my thumb. Don't dedect my thumb. My UMI is not any responds for thumb fingers. (May be works under sunlight, but if there is not sunlight, fingerprint is not works with thumb finger. And other fingers are not faster than iPhone. Sometimes not works.)


Edit: Not just for my thumb finger. Not works with every thumb fingers.
*Bonus question: How it can dedect thumb? Why just thumb? And why too much sun light is required for works with thumb?

I tried calibrate fingerprint and clean fingerprint sensor with microfibre cloth.
Please help for fix this.