Accessing PostgreSQL through Apache and PHP4 on Linux

I am running PostgreSQL 7.1.3, RedHat 7.1 (kernel 2.4.2-2), and
PHP/4.0.4pl1. When I try to run a PHP page found below I get an error that
says:

Fatal error: Call to undefined function: pg_connect() in
/var/www/html/psolver.php on line 10

Additionally, even though pgsql.so IS in /usr/lib/php4 (and php.ini tells
PHP to look there for extensions), I get the following error on the call to
dl().

Warning: Unable to load dynamic library '/usr/lib/php4/pgsql.so' - libpq.so:
cannot load shared object file: No such file or directory in
/var/www/html/psolver.php on line 7

Code snippet:
----------------------------------------------------------------------------
-------------------
<?
dl("pgsql.so");

//connect to database
$conn = pg_connect("","","","psolver");
if(!$conn) {
print("Couldn't connect to psolver");
exit;
}
?>