Unable to createlang

I am having a problem trying to create a language in a new install of Postgres
  - I have installed postgres 9.1 on a minimal (i.e. no GUI) CentOS 6.2 system.
  - Psql is running and I am able to connect to the database from pgAdmin running on a Windows box.
  - Postgres was installed in /opt/postgres
  - The data was placed in /var/postgres/data.

I am migrating a database from an 8.4 system to the new system. I am trying to add the plperl and plperlu languages,
whichare used in the 8.4 system.  

The command I am using is:

    createlang -U postgres plperl hf-hvpa

The message I get back is:

    createlang: language installation failed: ERROR:  could not load library "/opt/postgres/lib/postgresql/plperl.so":
libperl.so:cannot open shared object file: No such file or directory 

I am doing this as the root user, but I have also tried it using my login and as the postgres user. The plperl.so file
isin the indicated directory, but I am not sure what the reference to libperl.so means. Is that a separate file I need
todownload?  

I am fairy new to both Linux and Postgres, however I have successfully installed Postgres on a Windows systems.

Sincerely appreciate any help.

Tom Harkaway