Dell Latitude 5400 + plasma - keyboard?

[Hans <hans.ullrich@loop.de>]

Dear list,

is anyone by chance using a Dell Latitude 5400 with Plasma? 

I am looking for the keyboard setting for Debian wuith this hardware. The 
problem is, the Function-keys are not working. 

Not working means: The second level do not work like "volume higher/lower" 
"brightness" and so on.

The hotkey (which switches between both levels) Func+ESC is working.

The setting for keyboard is set to "Dell Latitude". 

Some weired thing: 

In console and in Plasma the Brightness can not be adjusted, but in XFCE it 
can. However, I could not get, which keyboard setting XFCE is using, does pne 
know?

In Debian WIKI I found no hints for the keyboard, and also no clues in other 
lists.

So I have the hope, someone by chance might own the same notebook or does 
more.

Thank you for any hints.

Best

Hans