Oracle Database Discussions

I have created an Oracle database on my Windows XP system but cannot connect from a php script I created

<?php
if (!$db = @ocilogon("big", "big", "s7s"))
    {
    $error = ocierror();
    printf("Error was: %s", $error["message"]);
    die();
    }

$stmt = ociparse($db,"SELECT count(*) FROM members");
ociexecute($stmt);
?>

When I created the database the connection I used was s7s but whether or not I include that name or just use the ID/password that script will not connect.
Please tell me what else I need to do to get this to work.