Check that there are no magnets around it.
Calibrate your stylus.
For A5 X & A6 X: Swipe down to bring up the top menu, go to the settings page, tap [Display & input], select "Stylus Calibration" and follow the prompts to complete the calibration.
For A5 & A6 Agile: Swipe down to bring up the top menu, go to the settings page, tap [Device Management], select "Stylus Calibration" and follow the prompts to complete the calibration.