Calculus detection!

Okay so for some reason I cannot for the life of me feel calculus! It is making me so frustrated right now...... :( I cant even feel if Im taking it off or not. My poor husband I just was poking him to death today haah. I had instructor snow tell me where the calculus was and then I went at it. I did use the ultrasonic today and I loved it. Im just gonna pray that I will be able to feel calculus someday.....