phpBB sessions do not carry from page to page
===

I have a website (located in the root directory) with a forum located in ./forum/

I have successfully integrated phpBB's sessions into the index of my website using the following codes:

In my index page before `<html>`:

    <?php include_once("include/phpbb.php");
    // check for logout request
    $cp = $_GET['cp'];
    // is it a logout? then kill the session!
    if ($cp == "logout") {
    $user->session_kill();
    $user->session_begin();
    echo "Successfully Logged Out.";
    }
    ?>

phpbb.php:

    <?php
    define('IN_PHPBB', true);
    $phpbb_root_path = (defined('PHPBB_ROOT_PATH')) ? PHPBB_ROOT_PATH :  '../forum/';
    $phpEx = substr(strrchr(__FILE__, '.'), 1);
    require($phpbb_root_path . 'common.' . $phpEx);
    // Start session management
    $user->session_begin();
    $auth->acl($user->data);
    $user->setup();
    $user->data['user_avatar']
    ?>

Displaying the information - this is in header.php which is included in my index:

    <?php
    // Page login notice
    if ($user->data['user_id'] == ANONYMOUS)
    {
    ?>
    
    <img src="forum/images/avatars/gallery/noavatar.png" style="float:left; width:72px; height:72px;">
    <div class="login">
    	<form method="POST" action="forum/ucp.php?mode=login">
    	<ul><li><span>Username:</span> <input class="loginfield" type="text" name="username" size="20"></li>
    		<li><span>Password:</span> <input class="loginfield" type="password" name="password" size="20"></li>
    		<li>Remember Me? <input type="checkbox" name="autologin"> &nbsp; &nbsp; &nbsp; <a href="forum/ucp.php?mode=register">Register</a></li>
    		<li><input type="submit" value="Login" name="login"></li>
    	</ul>
    	<input type="hidden" name="redirect" value="../index2.php">
    	</form>
    </div>	
    				
    <?php
    } else { ?>
    
    <img src="forum/images/avatars/gallery/<?php echo $user->data['user_avatar']; ?>" style="float:left; width:72px; height:72px;">
    <div class="login">
    	Welcome back, <?php echo $user->data['username_clean']; ?><br> 
    	You have <?php echo $user->data['user_unread_privmsg']; ?> new messages<br>
    	<a href="index2.php?cp=logout">Log Out</a>
    </div>
    <?php } ?>

I can successfully log in on the index using the form I created, but if I then click to another page (i.e. about.php) I am asked to log in again. This happens for every page. This also happens if I click over to the phpbb forum. 

Is there any way to make it so I can log in on any page, and not have the session restart when browsing other pages? 

Thank you for any help!