Common errors that may impact on your balance test results are outlined below: 

Moving to get the cross-hair in the very middle of the target on the screen:
The balance test measures how much the target moves, not if it’s at the centre. Focus on keeping the target still, regardless of where it is on the screen.   

Using different techniques: 
Different techniques used to maintain balance may have an impact on the overall score. Aim to keep the raised leg slightly off the platform by bending at the knee so your foot is behind you (not lifting from the hip with your knee raised in front of you) and ensure it is not touching the standing leg.