ofxOpenNI - kinect image freezes - more than one user


I’m using a kinect, openNI and NITE and ofxOpenNI wrapper (gameoverhack) to openframeworks in windows Vista.

I want to track a user and his movements (waving, etc…) Everything ok with movements, but I’m having a trouble with tracking a user.

Everything works fine when first user appears on scene. I can track user and use joints. But when the user goes out of the screen and I wait the normal time until i get the Lost User Callback, when another user gets in front of camera, there is a small freeze of the image and i get two new users, when there’s only 1 person in front of camera. This is a problem as i can’t track any user anymore…

In the logs there are some messages.
New User 1
Calibration requested for user1
Allocating mask texture for user1
New User 2

So i get a new user 2, don’t understand where from, and the program fails the calibration of user 1.

Can somebody help me on this? I don’t now if it is clear, but i can answer to any doubts or post some logs or code

Thanks in advance.