isset vs empty vs is_null
<p>I'm trying to write a script that when a user uploads a file and does not enter a name an error is returned. I've tried using is_null, empty, and isset and they all do not work. Eg, below, is_null returns an error even when a name is entered. Can anyone help?</p>

<pre><code>    $caption = $_REQUEST[$name_input_name];

 if(is_null($caption))
 {
 $file-&gt;error = 'Please Enter a Title';
 return false;
 }
</code></pre>
