Keep Getting A SQL Syntax Error : <p>I've tried many things but for some reason I can not figure out why the following code keeps giving me an error.</p>

<pre><code>$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn-&gt;connect_error) {
    die("Connection failed: " . $conn-&gt;connect_error);
} 

$sql = "INSERT INTO app_users (signupDate, userToken, ipAddress, countryCode, countryName, regionName, cityName, zipCode, latitude, longitude, timeZone, referer, userAgent, hostName)
VALUES ('$ls_signupDate', '$ls_userToken', '$ls_ipAddress', '$ls_countryCode', '$ls_countryName', '$ls_regionName', '$ls_cityName', '$ls_zipCode', '$ls_latitude', '$ls_longitude', '$ls_timeZone', '$ls_referer', '$ls_userAgent', '$ls_hostName)'";

if ($conn-&gt;query($sql) === TRUE) {
    echo "Content Inserted successfully";
} else {
    echo "Error inserting content: " . $conn-&gt;error;
}
</code></pre>

<p>The error it keeps giving me is...</p>

<blockquote>
  <p>You have an error in your SQL syntax; check the manual that
  corresponds to your MySQL server version for the right syntax to use
  near '' at line 2</p>
</blockquote>

<p><strong>What am I doing wrong here?</strong></p>
