Using pgaccess and xpg

Hello,

I have a question regarding settings which are necessary
to use pgaccess and/or xpg with existing database which is
located on localhost.
I can access the database by invoking psql with name of database
as well as through C++ program using libpqxx library.

Invoking xpg produces window Connection to PostgreSQL with
entries

Host localhost
Database database01
User postgres
Password
Port 5432

Replacing database01 and postgres with the existing User and
existing database produces error message
Connection refused. Check that the hostname and port is correct,
and that the postmaster is running with the -i flag which enables
TCP/IP networking.

If I invoke pgaccess > sh pgaccess.tcl I am getting the similar
message

Error trying to connect to database 'RabStudies' on host localhost

PostgreSQL error message: Connection to database failed
could not connect to server:
Is the server running on host "localhost"
and accepting TCP/IP connection
on port 5432?

My platform is Fedora Core 2, postgresql-7.4.2-1 installed from rpm.

I appreciate any comments.

Michal