UI buttons in Unity/Vuforia

Hello,

I'm trying to integrate UI buttons when Image target is detected. What I cannot do is figure it how to make that button follows Target image when I do that.

I have AR Camera, and Target image, and I've set child Canvas to Target Image, and set button as child to Canvas. What I get is button showing up when Target image is shown, and button disappears when target image is removed, but Button is on the same spot as set in Unity, as well as same size and angle. Nothing happens when I rotate Target image around.

Any help with this?

Thank you in advance.