Installing plpgsql language

hi again, although i re checked the permissions on the file plpgsql.so
(r/w/x), it doesnt work.. this is what i get when using the -e option:

SELECT oid FROM pg_language WHERE lanname = 'plpgsql';
SELECT oid FROM pg_proc WHERE proname = 'plpgsql_call_handler' AND
prorettype = 0 AND pronargs = 0;
SET autocommit TO 'on';CREATE FUNCTION "plpgsql_call_handler" ()
RETURNS LANGUAGE_HANDLER AS '$libdir/plpgsql' LANGUAGE C;
ERROR: Load of file /Library/PostgreSQL/lib/postgresql/plpgsql.so
failed: no error message available
createlang: language installation failed

help me please!

thanks

JuanF