pg_connect works, DBI::connect says permission denied

Hello,
I'm having problems connecting to my Postgres database using DBI::connect in
Perl.

--------------------------------------------------------------------------------------------------------------------------------------------------
DBI connect('dbname=visualizer','visualizer',...) failed: could not connect
to server: Permission denied
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
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Two important things to note:
1) The permissions on both the /tmp directory and the socket file are 777
(full access)
2) I can connect to the same database just fine using pg_connect in PHP

I just installed everything on a new server, and everything worked fine on
the old one.
I figure I missed some configuration detail somewhere. Any ideas?

Here are the versions I'm using:
PostgreSQL 7.4.8
PHP 4.3.9
Perl 5.8.5
Don't remember which version of Redhat I have

Thanks in advance for your consideration,
RYan Miller