Text component unreadable on device (blocks instead of actual text)

I’ve been trying this tutorial to display texts on the 4 corners of the screen.

It’s working fine on the editor with holographic emulator.
But when I build to device, I get purple rectangles instead of actual text.

Screnshots
On device

On the editor

Any ideas ?

So, it was missing material/shader in the text material box. It seems that everytime somehting is pink in unity, it’s a missing shader problem.