title: $_POST array is sometimes empty
body: <p>When submitting my form, sometimes the <code>$_POST</code> array is empty and other times it's not (when inputting the exact same thing on the exact same input). 
  My <code>post_max_size</code> is large <code>500M</code> and I'm only inputting values from checkboxes. What could be causing this? I might have thought it was because of a <code>for</code> loop I'm using, but the <code>$_POST</code> array is fine half the time and empty the other.</p>
  
  <pre><code> &lt;form action="send.php" method="post" enctype="multipart/form-data"&gt;
      &lt;input type="checkbox" name="Facebook" value="Facebook" id="Facebook"/&gt;
      &lt;input type="checkbox" name="Twitter" value="Twitter" id="Twitter"/&gt;
      &lt;?php
      for($i = 0; $i &lt; $blogcount; $i = $i + 1){
      echo '&lt;input type="checkbox" name="Tumblr[]" value="'.$bloglist[$i].'" id="Tumblr'.$bloglist[$i].'"/&gt;';
      } 
      ?&gt;
      &lt;input id="myImage" type="file" accept="image/*" name="file" class="upload" /&gt;
      &lt;input type="submit"&gt;
  &lt;/form&gt;
  </code></pre>