MCT8316AEVM: How to use PWM input mode and Frequency input mode with MCT8316AEVM

Hello, I have a problem with rotating motor using MCT8316AEVM.  I was able to drive a motor with analog input and I2C input modes.  However, I could not start rotating a motor with PWM input and frequency input modes.  I used a function generator(FG) to send a signal.  I connected a positive pole of FG to SPEED_IN pin and a negative pole of FG to SPEED pin.   Could you tell me whether it is wrong or not?  Thank you.