Case sensitive order by

Hi,

I have a problem with a case sensitive 'order by'.
On my development platform, the 'order by' clauses are insensitive
But on my production platform, they are case sensitive.
I did the same installation on both platforms, from RPMs I downloaded
(Postgresql 7.1  on Redhat 7.0).
I tried to set LC_COLLATE=C before initdb, but nothing changed.

Is there a configuration for that ? Is it a specific parameter on my system
?

Any help will be appreciated

Thank's a lot.