Hungarian o and u double accute doesn't display correctly

[Csanyi Pal]

Hi,

I'm developing an aplication that shall have graphical user interface on
many languages. 

Currently it supports Hungarian, English and Serbian Latin.

When start the application on Debian GNU/Linux Squeeze, the characters:
o double accute and u double accute doesn't display correctly. Instead
of these characters one can se a rectangular shape.

On my old laptop I have Debian GNU/Linux Squeeze too, and there the on
GUI I can see these characters properly. OK, I haven't update this
system recently, but my Desktop Debian GNU/Linux Squeeze is up to date
and there appeares this problem.

How can I solve this problem?

Any advices will be appreciated!

-- 
Regards, Paul Chany
http://www.debian.org
http://wiki.debian.org/DebianEdu
http://csanyi-pal.info