need help on my postgres on centos 4.3

I am totally new to postgres and need help to fix a problem comes from
rake command. This morning I installed postgres 8.2 on my centos 4.3
box.

the steps I used to install postgres are as follows:

1) wget postgresql-8.2.2.tar.gz from postgres.org
2) tar -zxf postgresql-8.2.2.tar.gz
3) yum install flex
4) ./configure --prefix=/usr/local/pgsql --without-readline
5) gmake
6) gmake install
7) export POSTGRES_INCLUDE=/usr/local/pgsql/include/
8) export POSTGRES_LIB=/usr/local/pgsql/lib/
9) export LD_LIBRARY_PATH=/usr/local/pgsql/lib/
10)gem install ruby-postgres

everything was fine. after that, I started postgresql and created a test
db:

CREATE DATABASE "test_developent" WITH ENCODING='UNICODE'
OWNER=postgres;

it was ok too.

then, rails test --database=postgresql

it was successfully as well.

when I test rake db:migrate, I got the following error message:

(in /usr/local/html/test)
rake aborted!
libpq.so.5: cannot open shared object file: No such file or directory -
/usr/lib64/ruby/gems/1.8/gems/ruby-postgres-0.7.1.2006.04.06/./postgres.so

I found postgres.so is located at folder ruby-postgres-0.7.1.2006.04.06,
no idea why there is a "./" before postgres.so. any one could help me
out? thanks.