Formatted output with locale

[dev]

Hi there,
I have problems to get a proper formatting using the (ice-9 format)
module. In my code, I need to deal with monetary figures, but I fail
to get the correct format for my German locale.
Let's say I have one hundred thousand Euros. The correct format to output
this in de_DE.utf-8 would be
100.000,00 EUR
(with 2 decimals)

Now I tried:
(setlocale LC_ALL "de_DE.UTF-8")
(use-modules (ice-9 format))
(define a 100000.00)
(format #t "~12,2h EUR~%" a)
(format #t "~,,12$ EUR~%" a)
(format #t "~12,2f EUR~%" a)

But this is what Guile gives to me:
   100.000,0 EUR
   100000.00 EUR
   100000.00 EUR

None is correct. What did I miss? 
-Martin