Lyx doesn't compile its own example handbook - colored-boxes.lyx

Hi,

Lyx does not compile its own manual for "Farbige Boxen". Compiling other 
manuals is ok.

The error message is: Package pgfkeys Error: Choice 'scale' unknown in 
choice key '/tcb/valign'. I


\begin{tcolorbox}[height=2cm, valign=scale]

This error message was generated by an \errmessage

command, so I can't give any explicit help.

Pretend that you're Hercule Poirot: Examine all clues,

and deduce the truth by order and method.

When i change the source to : \begin{tcolorbox}[height=2cm]

it compiles, but it is not what it has to be.

What have i to do to compile examples/colored-boxes.lyx out of the box?

Greetings,

G. Pötting