Pgpool install - libpq is not installed or libpq is old

Based on the documentation here , I want to create a pgpool II with PostgreSQL databases. When I try to install, I encounter this error: configure: error: libpq is not installed or libpq is old Searching the pgpool website, they mention to run ./configure with this command: --with-pgsql OR --with-pgsql-includedir OR --with-pgsql-libdir But still I'm facing the same problem. Can anyone guide me what can I do from here? I am running PostgreSQL 9.2 intalled from a yum package on CentOS 5.