There are some reasons :

1. Make sure your feet are bare. Remove the socks.

2. Stand firmly on the scale with feet apart, facing the LED digital display.

3. Do not step down from scale before required measurement time ( approx. 15~20 sec)

4. If your feet are too dry then kindly moisten your footprint and then try to measure again. 

5. Ask another person to step on the scale and see if the body fat data work for them.

6. Remove the plastic cover if not removed.