plpgsql cannot stat plpgsql.so - Mailing list pgsql-admin

I am defining some triggers in Postgres 6.4.2 on Solaris 2.6, but when
the trigger is set off, I get an error:

ERROR:  stat failed on file ${exec_prefix}/lib/plpgsql.so

the permissions are 644 on above file. I have added the language to the
database.

Can you give me any suggestions? I would rather not upgrade at this
point - It is working so well!

Marc Wrubleski