prob with PERL/Postgres

PERL SNIPPET:

# build arrays from file (OMITTED)

use Pg;
$dbhost='127.0.0.1';
$dbname='mpact';
#$connstr="dbname=$dbname";
$connstr="host=$dbhost dbname=$dbname";
$conn = Pg::connectdb($connstr);

#more code related to date omitted

$result=$conn->exec($sql);
(PGRES_COMMAND_OK eq $result->resultStatus)
or die $conn->errorMessage;

WHY DO I GET PQsendQuery() -- There is no connection to the
backend. I have tried leaving host blank, using IP 127.0.0.1 and
hostname localhost. This script should work - the problem is
something with postgres but I dont know what. Any ideas out
there? Thanks, Kris