title: Fatal error: Call to undefined function
body: <p>I have this </p>
  
  <blockquote>
    <p>Fatal error: Call to undefined function date_add() in
    /home/....../public_html/wp-content/plugins/wp-ads/admin/edit-ad-update.php
    on line 70</p>
  </blockquote>
  
  <p>The line have the folowing code:</p>
  
  <pre><code>date_add($ad_data["real_end_date"], new DateInterval("P".$ad_plan-&gt;days_length."D"));
  </code></pre>
  
  <p>Can some one help me?</p>