I can't make a stable calibration on foots with HTC VIVE TRACKERS

[ukfdr]

Hello All, 

I've been developing an application using HTC Vive Trackers on Foots.

When you play the scene the first thing I made user do is make a calibration. 

then user make sure that the trackers are on the right places. 

and on the next step, user select a scene to play and gets in and play. However, when user gets back to main menu I loose the calibration states of the trackers and user should calibrate it again before selecting next scene. 

What am I probobly missing, can you please help me?

Kind regards, 

ukfdr.