I am trying to put a signup.php section on my website. The script dies somewhere in the php code, and i've been trying to figure it out for hours with no luck.

The script dies somewhere in here because when i throw this in the file and ftp it to the server and run it, the page comes back blank.
PHP Code:
 <?php 
include_once("scripts/connect_to_mysql.php");
$message ='';

if(isset(
$_POST['username'])){

    
$username $_POST['username'];
    
$fname $_POST['fname'];
    
$lname $_POST['lname'];
    
$email $_POST['email'];
    
$pass1 $_POST['pass1'];
    
$pass2 $_POST['pass2'];
    
    
//error handling
    
if((!$username)||(!$fname)||(!$lname)||(!$email)||(!$pass1)||(!$pass2)){
        
$message='Please insert all fields into the form below.';
    }else{
        if(
$pass1 != $pass2){
            
$message ='Your password fields do not match.';
        }else{
            
//securing the values of the variables
            
$username preg_replace("#[^0-9a-z]#i","",$username);
            
$fname preg_replace("#[^0-9a-z]#i","",$fname);
            
$lname preg_replace("#[^0-9a-z]#i","",$lname);
            
$pass1 sha($pass1);
            
$email mysql_real_escape_string($email);
            
            
//check duplicates
            
$user_query mysql_query("SELECT username FROM members WHERE username='$username' LIMIT 1")or die("Could not check username");
            
$count_username mysql_num_rows($user_query);
            
            
$user_query mysql_query("SELECT email FROM members WHERE email='$email' LIMIT 1")or die("Could not check Email");
            
$count_email mysql_num_rows($email_query);
            
            if(
$count_username 0){
                
$message ='Your username already exists.';
            }else if(
$count_email 0){
                
$message ='Your email already exists.';
            }else{
                
// insert users
                
$query mysql_query("INSERT INTO members (username, fname, lname, email, password, lastlogin, accounttype, emailactivated, joindate) VALUES('$username', '$fname', '$lname', '$email', '$password', '', '', '', now())")or die("Could not insert data.");
                
$member_id mysql_insert_id();
                
mkdir("users/$member_id",0755);
                
$message ='You have now been registered.';
            }
        }
?>
and here is the form in the body section
Code:
<div>
Register to my site by filling in the fields below.
	<p><?php print("$message");?></p>
	<form action="register2.php" method="post">
	<input type="text" name="username" placeholder="Username"/><br />
        <input type="text" name="fname" placeholder="First Name"/><br />
        <input type="text" name="lname" placeholder="Last Name"/><br />
        <input type="text" name="email" placeholder="Email Address"/><br />
        <input type="password" name="pass1" placeholder="Password"/><br />
        <input type="password" name="pass2" placeholder="Validate your password"/><br />
        <input type="submit" value="Register" />


	</form>
</div>