password authentication always failed

Hi,
I have superuser named postgres and normal user named garfield.
Then I do this in command prompt :
$ su postgres
$ initdb -D /usr/local/pgsql/proj -U garfield
$ psql -U garfield -f mydb.sql template1
$ psql -U garfield mydb

Ok, everything is fine.... I can connect to database and do some
operation.
Note: mydb.sql was created with this command before:
$ pg_dump -u -C -f mydb.sql mydb

Then I changed the pg_hba.conf in /usr/local/pgsql/proj from :
# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD

# "local" is for Unix domain socket connections only
local   all         all                               trust
# IPv4 local connections:
host    all         all         127.0.0.1/32          trust
# IPv6 local connections:
host    all         all         ::1/128               trust

to
# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD

# "local" is for Unix domain socket connections only
local   all         all                               md5
# IPv4 local connections:
host    all         all         127.0.0.1/32          trust
# IPv6 local connections:
host    all         all         ::1/128               trust

Then I restarted database. When I do this command:
$ psql -U garfield mydb
password:
It always failed with error:
FATAL:  password authentication failed for user "garfield"
psql: FATAL:  password authentication failed for user "garfield"

I have done this as postgres to make sure that password is correct:
# ALTER USER garfield PASSWORD 'garfield' CREATEDB;

What is wrong? garfield can create database but not another user.
Could that be problem?????

Thank you.

Regards,

Akbar