Bash script call to php not returning values

Please can anyone help with this? Trying to auth OpenVPN from a mysql database (wordpress). Have followed this guide
and all scripts etc seems to be working apart from OpenVPN authing at the end.

1: Remote User enters login details in OpenVPN client and tries to connect to server

2: OpenVPN Server saves login details to TMP file, and calls “Helper” script

3: Helper script grabs username & password from TMP file, passes to to “Auth” script to verify & get Result

4: Auth script verifies with MySQL database and gives result to Helper script

5: Helper script tells OpenVPN to allow or deny

If I try log in to OpenVPN, auth fails.
I can monitor the MySQL and see the query being run so its all good until step 4. So you might think Helper isnt giving a result.
But I know that Helper script can output a result because, if I fill in variables manually (and run the Helper script from command line), the Auth script runs the query, and a result is received and outputted to command line!

So in theory, every step is working.
it IS giving an output.
So why on earth when I try to log in with OpenVPN client, it doesnt work?
After all, I can monitor MYSQL and I see the query being run, and I know that step 5 CAN and does output a result. So it should be working!

Any idea what could be wrong please?

Helper script:

TMPFILE=""         # OpenVPN temp file
WPPATH="/var/www/html/rvpn"   # Use full path here, _without_ last slash "/"

# Get basedir for "vpnauth.php"
#BASEDIR=$(/etc/openvpn $0)
VPNUSER="`head -n1 ${TMPFILE} | tail -n1`" # first line
VPNPASS="`head -n2 ${TMPFILE} | tail -n1`" # second line

# Getting results from PHP script
RESULT="`php -f /etc/openvpn/vpnauth.php "${WPPATH}" "${VPNUSER}" "${VPNPASS}"`"
echo "$RESULT"

AUth script:

    $_SERVER['HTTP_HOST'] = 'rvpn_';      // apache and table prefix: "wp_" is the default


// Getting variables arguments
$wordpressdir = $argv[1]; // IGNORE THIS. Not used at present.
$openvpn_user = $argv[2];
$openvpn_pass = $argv[3];

require_once( '/var/www/html/rvpn/wp-load.php' ); // you need to adjust this to your path

// If the query returns username, this user can connect to VPN AFTER PASSWORD CHECK. That's next.
$userresult = $wpdb->get_var( "SELECT user_login FROM rvpn_users WHERE ( (vpn_credit > 0) AND (vpn_enabled = 1) AND (user_login = '$openvpn_user') );" );
// If not empty
if ($userresult) {
   $user = get_user_by('login', "$userresult");
   if ( wp_check_password( "$openvpn_pass", $user->data->user_pass, $user->ID) )
      // Password match
      echo "xOKx";
     // Wrong password
      echo "xWRONGPASSx";

   } else {
   // Woops. User not found
   echo "xWRONGUSERx";

Source: stackoverflow-php