Fatal error: Call to a member function execute() on boolean on line 33 : <p>I've been getting one warning and one fatal error when trying to run the execute() command. I can't seem to find the error at my stm->execute();</p>

<p>Here are my errors:</p>

<blockquote>
  <p>Warning: mysqli_stmt::bind_param(): Invalid type or no types specified in C:\xampp\htdocs\library\admin-reg.php on line 20</p>
  
  <p>Fatal error: Call to a member function execute() on boolean in
  C:\xampp\htdocs\library\admin-reg.php on line 33</p>
</blockquote>

<p>Then this is a snippet of my code.</p>

<pre><code> &lt;?php
                                                #CONNECTION    
    require 'dbcon.php';

                                                #INPUT CONTAINERS
    $ACTIVATION_CODE=$USERNAME=$PASSWORD=$EMAIL=$FIRST_NAME=$MIDDLE_NAME=$LAST_NAME=$CONTACT_NO=$ADDRESS=$PROFILE='';

                                                #ERROR CONTAINERS
    $USERNAME=$PASSWORD=$EMAIL=$FIRST_NAME=$MIDDLE_NAME=$LAST_NAME=$CONTACT_NO=$ADDRESS=$PROFILE=$USER_TYPE='';

                                                #CONNECTION/QUERY#
    $connection = mysqli_connect('localhost','root','','library_system') or die(mysqli_error());    
    $stm = $mysli_link-&gt;prepare("INSERT INTO users (username,password,first_name,middle_name,last_name,address,contact_no,email,activation_code) values(?,?,?,?,?,?,?,?,?)");
    $stm = $stm-&gt;bind_param($USERNAME,$PASSWORD,$FIRST_NAME,$MIDDLE_NAME,$LAST_NAME,$ADDRESS,$CONTACT_NO,$EMAIL,$ACTIVATION_CODE);
                                                #VERIFICATION SCRIPT
    IF(isset($_POST['register'])){
        $USERNAME = trim(mysqli_real_escape_string($connection,$_POST['username']));
        $PASSWORD = trim(mysqli_real_escape_string($connection,password_hash($_POST['password'],PASSWORD_DEFAULT)));
        $EMAIL = trim(mysqli_real_escape_string($connection,$_POST['email']));
        $FIRST_NAME = mysqli_real_escape_string($connection,$_POST['first_name']);
        $MIDDLE_NAME = mysqli_real_escape_string($connection,$_POST['middle_name']);
        $LAST_NAME = mysqli_real_escape_string($connection,$_POST['last_name']);
        $CONTACT_NO = trim(mysqli_real_escape_string($connection,$_POST['contact_no']));
        $ADDRESS = mysqli_real_escape_string($connection,$_POST['address']);            
        $ACTIVATION_CODE = md5($USERNAME.(rand(0,1000)));
        $USER_TYPE = "ADMIN";
        $stm-&gt;execute();                                            

    }

?&gt;
</code></pre>

<p>Hope you can help me.</p>
