extension pam.so::: pam_auth Error

Server : CentOS 5.3 FINAL
httpd: APACHE 2.2
php: 5.2.9
pecl install PAM


I have some small code just for testing

if (pam_auth("user", "password", &$error)) {
echo "Yeah baby, we're authenticated!";
} else {
echo $error;
}


Permission denied (in pam_authenticate)

Has any one done this and know how to fix this error im running php in suExec as root so i don't get how i can get this error