Z-Wave dimmer only respond to ON/OFF under OpenHAB 2

I have three plug-in dimmers that I am testing under openHAB 2. I copied the lines from my openHAB 1.7 into the items/demo.items of the demo setup.
I also copied the lines that I had in the sitemap into the openHAB 2 one.

The three dimmer will respond to the ON and OFF commands but not any of the dimming values.
Here is an example of log I see:

2015-11-16 19:23:41.546 [INFO ] [runtime.busevents ] - PlugIn_Dimmer_1 received command OFF
2015-11-16 19:23:41.547 [INFO ] [runtime.busevents ] - PlugIn_Dimmer_1 state updated to OFF

And the dimmer is off. If now, I move the slider to 50%, the log says:

2015-11-16 19:24:46.870 [INFO ] [runtime.busevents ] - PlugIn_Dimmer_1 received command 50

But nothing happens. Turning ON the dimmer will work like the OFF command and the log says

2015-11-16 19:26:05.656 [INFO ] [runtime.busevents ] - PlugIn_Dimmer_1 received command ON

And that works.
The node?.xml files are the same except for the order of entry items and heal and LastSent, LastReceive.

What am I forgetting (if anything?)