PHP PDO Common Error i Faced - php

Question

I gotten this error
Database Connected successfully Fatal error: Call to a member function prepare() on a non-object in D:\home\site\wwwroot\DatabaseMethods.php on line 22
I can't seem to find what is causing this any one could point out whats wrong please enlighten me.
I have tried to call the connection before running the prepared statement but cant seems to work or what should i do
Thanks in advance
DatabaseMethods.php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);
require_once("DatabaseConnection.php");
date_default_timezone_set("Asia/Singapore");
//Register
function RegisterUser($email , $password)
{
$conn = connect_db();
$stmt = null;
$stmt = $conn->prepare("INSERT INTO secure_login (email,password,created_dt) VALUES(?,?,?)"); //ERROR LINE
$stmt->execute(array($email, $password , date("Y-m-d h:i:s")));
if( $stmt )
{
return "success";
}
else
{
return "Failed";
}
}
//date("Y-m-d h:i:s")
//End Register
?>
DatabaseConnection.php
<?php
function connect_db()
{
$servername = "xxxx";
$username = "xxx";
$password = "xxx";
try {
$conn = new PDO("mysql:host=$servername;dbname=xxx", $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Database Connected successfully";
}
catch(PDOException $e)
{
echo "Connection failed: " . $e->getMessage();
}
}
?>
Answer
<?php
function connect_db()
{
$servername = "xxx";
$username = "xxx";
$password = "xxx";
try {
$conn = new PDO("mysql:host=$servername;dbname=xxx", $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Database Connected successfully";
return $conn;
}
catch(PDOException $e)
{
echo "Connection failed: " . $e->getMessage();
}
}
?>