Multiple Postmasters

I am attempting to create a database server with multiple harddrives where
each hard drive has an instance of postmaster managing the database cluster
on that drive.  Currently i am trying to get this scenario to work with two
instances, and after i get confidence that it will work i will do it for
more.

My environment is Linux 7.1 with PostgreSql 7.0.3

The database superuser is postgres and i create two environment variables
for that user

PGA=/bar/data
PGB=/foo/data

export PGA PGB

I create the data directory in each area and initdb each of the areas.

I copied /etc/rc.d/init.d/postgresql to postgrea and postgreb and changed
all references of
PGDATA to PGA and PGB respectively.  Also changes the hard paths to point to
the correct place.

I modified postmaster.opts.default to include options for a different port
for each instance of postmaster in the appropriate data areas.

I linked startup and shutdown deamons in the rc5.d and rc6.d directories,
rebooted and linux started each instance of postmaster as expected
/usr/bin/postmaster -i -p 5433
/usr/bin/postmaster -i -p 5434

I then logged in as postgres and initlocation on each data area.

I then attempted to create a user for each location

createuser -p 5433 abc
psql: connectDBStart ( ) -- connect() failed: No such file or directory
    Is the postmaster running at 'localhost'
    and accepting connections on Unix socket '5433'?
createuser: creation of user "abc" failed

createuser -p 5434 abc
CREATE USER

the second instance works and the first instance didn't.

Im stumped at this point.  Help please.