OnMouseDown not work in Vuforia

I have a problem with Unity3D. I'm working on an AR project with Vuforia+Unity and I was testing the OnDownMouse() event so that when I play the GameObject and do an action, in this case just Debug.Log() to try. But this only works the first time, and the second time I give play to try it doesn't work. I've been looking at the colliders and they're well configured. Another thing I noticed is that the script check disappears what I suspect may be the problem. ![alt text][1] This is my repository, branch develop: https://github.com/emicalvacho/MapaMentalAR.git [1]: /storage/temp/145825-3.png