Setting Datestyle failed

Hello, it is me again :-)
Setting a different Datestyle now failes (7.0.2).
If I set a different Datestyle (e.g. European) either from the
Backend (postmaster -o -e ...) or in psql with "set
datestyle=European"),
the setting is completely  ignored. It seems as if the Style has been
set
as a "show datestyle" displays the correct setting. 
No matter what setting is choosed the output always looks the same.

Greetings, 
   Holger

My System: Sparc Solaris 2.6, PostgreSQL 7.0.2, gcc 2.95.2