Error 500 when performing Mysqli Queries
<p>I've been working on a tiny form fetch and insert to MySQL database system with PHP. I've made this type of code work before on a local WAMP server and now I'm trying to do it for real this time on my hosting, but I keep getting the 500 Error Internal Server error with the following code.</p>

<p>HTML: </p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html lang="en"&gt;
&lt;head&gt;
    &lt;meta charset="utf-8"&gt;
    &lt;meta http-equiv="X-UA-Compatible" content="IE=edge"&gt;
    &lt;meta name="viewport" content="width=device-width, initial-scale=1"&gt;
    &lt;link href="css/bootstrap.min.css" rel="stylesheet"&gt;
    &lt;link rel="stylesheet" type="text/css" href="Main_Stylesheet.css"&gt;
    &lt;script   src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"&gt;&lt;/script&gt;
    &lt;script src="js/bootstrap.min.js"&gt;&lt;/script&gt;
    &lt;title&gt;Contact&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;nav class="navbar navbar-default" id="Body_Nav" style="margin-bottom: none;"&gt;
        &lt;div class="container-fluid"&gt;
            &lt;div class="navbar-header"&gt;
                &lt;a class="navbar-brand" href="index.php"&gt;Filosofie in Amsterdam&lt;/a&gt;
                &lt;button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#myNavbar"&gt;
                &lt;span class="icon-bar"&gt;&lt;/span&gt;
                &lt;span class="icon-bar"&gt;&lt;/span&gt;
                &lt;span class="icon-bar"&gt;&lt;/span&gt; 
                &lt;/button&gt;
            &lt;/div&gt;
            &lt;div class="collapse navbar-collapse" id="myNavbar" &gt;
            &lt;ul class="nav navbar-nav"&gt;
                &lt;li&gt;&lt;a href="index.php"&gt;Home&lt;/a&gt;&lt;/li&gt;
                &lt;li&gt;&lt;a href="bestel.php"&gt;Bestel&lt;/a&gt;&lt;/li&gt;
                &lt;li&gt;&lt;a href="preview.php"&gt;Preview&lt;/a&gt;&lt;/li&gt;
                &lt;li class="active"&gt;&lt;a href="contact.php"&gt;Contact&lt;/a&gt;&lt;/li&gt;
                &lt;li&gt;&lt;a href="us.php"&gt;Over Ons&lt;/a&gt;&lt;/li&gt;
                &lt;li&gt;&lt;a href="donate.php"&gt;Doneren&lt;/a&gt;&lt;/li&gt;
            &lt;/ul&gt;
            &lt;/div&gt;
        &lt;/div&gt;
    &lt;/nav&gt;
    &lt;div class="container-fluid" id="Contact_Main_Header"&gt;
        &lt;div class="row"&gt;
            &lt;div class="col-lg-12"&gt;
                &lt;h1 class="text-center" id="Contact_Main_Header_H1"&gt;Contact&lt;/h1&gt;
            &lt;/div&gt;
        &lt;/div&gt;    
    &lt;/div&gt;
    &lt;div class="container"&gt;
        &lt;div class="row"&gt;
            &lt;div class="col-lg-6"&gt;
                &lt;h2 class="text-center"&gt;Informatie&lt;/h2&gt;
            &lt;/div&gt;
            &lt;div class="col-lg-6"&gt;
                &lt;h2 class="text-center"&gt;Nieuwsbrief&lt;/h2&gt;
                &lt;p class="text-justify"&gt;Op de hoogte zijn van voortgang of het laatste nieuws? Geef je dan op via de nieuwsbrief hieronder:&lt;/p&gt;
                &lt;form method="post" action="formvalid.php"&gt;
                    &lt;div class="form-group"&gt;
                        &lt;label for="Contact_Form_Email"&gt;Email Adres:&lt;/label&gt;
                        &lt;input type="email" name="Contact_Form_Email" class="form-control" id="Contact_Form_Email" placeholder="Plaats hier je email adres" required&gt;
                    &lt;/div&gt;    
                    &lt;div class="form-group"&gt;
                        &lt;label for="Contact_Form_First_Name"&gt;Voornaam:&lt;/label&gt;
                        &lt;input type="text" name="Contact_Form_First_Name" class="form-control" id="Contact_Form_First_Name" placeholder="Plaats hier je voornaam" required&gt;   
                    &lt;/div&gt;
                    &lt;div class="form-group"&gt;
                        &lt;label for="Contact_Form_Last_Name"&gt;Achternaam:&lt;/label&gt;
                        &lt;input type="text" name="Contact_Form_Last_Name" class="form-control" id="Contact_Form_Last_Name" placeholder="Plaats hier je voornaam" required&gt;
                    &lt;/div&gt;    
                    &lt;button type="submit" class="btn btn-default"&gt;Verzenden&lt;/button&gt;
                &lt;/form&gt;
            &lt;/div&gt;
        &lt;/div&gt;
    &lt;/div&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>And the PHP:</p>

<pre><code> &lt;?php
 $Server = "localhost";
 $Username = "filoso1q_admin";
 $PW = "Foxtrot15";
 $DB = "filoso1q_nieuwsbrief";
 $connection = mysqli_connect($Server, $Username, $PW, $DB);

 if($connection = false) {
     die("Error: " . mysqli_error_connect());
 }  

 $Email = $_POST("Contact_Form_Email");
 $First_Name = $_POST("Contact_Form_First_Name");
 $Last_Name = $_POST("Contact_Form_Last_Name");

 $sql = "INSERT INTO `Users` ('User_ID', 'Email', 'First_Name', 'Last_Name')  VALUES (NULL, '$Email', '$First_Name',  '$Last_Name');";

 mysqli_query($sql);

 mysqli_close($connection);
 ?&gt;
</code></pre>

<p>I'm pretty certain that some of this should work, but for some reason I can only run queries in PHPmyadmin itself. The host I have uses the Cpanel webadmin for the webserver.</p>