[pgrouting-users] debuging connection script with pgcluster/--cluster option

I have two versions of postgres installed, 8.4 and 9.1 installed on the
same machine

To connect to my 9.1 database, I defined the envromental variable


I have try saying

define("PG_OPTIONS" , "--cluster=9.1/main");

and using the phrase

  $con = pg_connect("dbname=".PG_DB." host=".PG_HOST." user=".PG_USER."

to connect to postgres, I get the error

[Mon Feb 06 22:37:40 2012] [error] [client] PHP Warning:
pg_connect(): Unable to connect to PostgreSQL server: FATAL: unrecognised
configuration parameter "cluster" in /var/www/re/php/pgrouting.php on line
33, referer:

Any suggestions as to the correct way of connecting to postgres?