Errors installing contrib

Hi All;

I've gone into contribs/pg_buffercache and run this:

make (as postgres)
make install (as root)
psql -f pg_buffercache.sql <my_db>

when I run the psql command against my database I get this:

BEGIN
SET
psql:pg_buffercache.sql:9: ERROR: could not access file "$libdir/
pg_buffercache": No such file or directory
psql:pg_buffercache.sql:15: ERROR: current transaction is aborted,
commands ignored until end of transaction block
psql:pg_buffercache.sql:18: ERROR: current transaction is aborted,
commands ignored until end of transaction block
psql:pg_buffercache.sql:19: ERROR: current transaction is aborted,
commands ignored until end of transaction block
ROLLBACK

Any thoughts ?

Thanks in advance...