Hello all, I am getting the above error while I was trying to make a login system.

These are my codes.

HTML Code:
        
		<!-- Website Navigation Bar placed here -->
	
		<div class="container">
			<div class="navbar navbar-inverse">
				<div class="navbar-inner">
					<div class="container" style="width: auto">       
						<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
							<span class="icon-bar"></span>
							<span class="icon-bar"></span>
							<span class="icon-bar"></span>
						</a>
						<div class="nav-collapse collapse">
						<ul class="nav">
							<li><a href="http://ankursinha.net/tofsis/index.php"><strong>Home</strong></a></li>
							<li><a href="http://ankursinha.net/tofsis/index.php"><strong>Downloads</strong></a></li>
						</ul> 
<?php 
	if(logged_in() === true) 
	{
		include $_SERVER["DOCUMENT_ROOT"].'/tofsis/faculty_logged_in.php';
	} 
	else 
	{
		include $_SERVER["DOCUMENT_ROOT"].'/tofsis/logged_out.php'; 
	}
?>					
Based on whether the person is logged in or not, the dropdown changes. Those codes are below.

If logged in:

HTML Code:
							<ul class="nav pull-right" role="navigation">
		    					<li class="dropdown">
		    						<a href="#" id="link1" role="button" class="dropdown-toggle" data-toggle="dropdown">
		    							<strong>Hi, <?php echo $user_data['faculty_fname']; ?></strong>
		    							<b class="caret"></b>
		    						</a>
		    						<ul class="dropdown-menu" role="menu">
		    							<li><a href="changepass.php">Change Password</a></li>
		    							<li><a href="logout.php">Log Out</a></li>
		    						</ul>
		    					</li>
							</ul>
                        </div>
                    </div>
                </div>
            </div>
        </div>
If not logged in:

HTML Code:
							<ul class="nav pull-right" role="navigation">
		    					<li class="dropdown">
		    						<a href="#" id="link1" role="button" class="dropdown-toggle" data-toggle="dropdown">
		    							<strong>Hi, <?php echo $user_data['faculty_fname']; ?></strong>
		    							<b class="caret"></b>
		    						</a>
		    						<ul class="dropdown-menu" role="menu">
		    							<li><a href="flogin.php">Faculty Login</a></li>
		    							<li><a href="slogin.php">Student Login</a></li>
		    						</ul>
		    					</li>
							</ul>
                        </div>
                    </div>
                </div>
            </div>
        </div>
And this is my logged in function:

HTML Code:
function logged_in() {
		return (isset($_SESSION['faculty_id'])) ? true : false ;
	}
Thing is no matter I am logged in or not, I still get the same error.

Here is the site link: http://ankursinha.net/tofsis/

Please help me solve this problem. The code ran perfectly on my localhost having PHP 5.3, but I am facing problem on the webserver having PHP 5.3 though I think the version is not the problem here.