AR Tracked image status ?

Hi

I am creating a very simple application which display an object on an traquable image. If the traquable image is detected on the screen, i will update the actor transform, If not, i will hide the actor.

My problem is the following:

After have tracked the traquable image, if after the image is not on the screen, the actor will stay on the position of the last time we saw the image.

So basically, i would like to hide the actor if the traquable image is not deteced on the screen.

HELP. (Check the screens)