How to eliminate the inaccuracy of PlaneSensor on SmartComponent

setyowmv

In my project I used a PlaneSensor to stop the movement of an object.
But I noticed that the object stop not exactly at the Position of the PlaneSensor but around 2mm to 12mm after the PlaneSensor. It varies from one Sensor to another.
I tried to move the Sensor to the "x" mm but the object only stop at the same inaccuracy or reduced inaccuracy.
anyway to eliminate this inaccuracy on the PlaneSensor?
I use the PlaneSensor on SmartComponent