Drupal: File upload required?

[OrithLott]

For some reason, my form breaks when I try to make a file upload required. Here is the code for it:\[code\]$form_id = "upload_form";$form[$form_id] = array ( '#type' => 'fieldset', '#description' => t('This is a utility to import nodes from a Comma Separated Value file. To begin, pick a node type, and upload a CSV.'),);$form[$form_id]['type'] = array( '#title' => t('Enter node type'), '#type' => 'textfield',// '#autocomplete_path' => '', TODO: autocomplete for node types '#required' => TRUE, '#description' => t('This node type should already exist. If it doesn\'t, create it first.'),);$form[$form_id]['upload'] = array( '#type' => 'file', '#title' => t('Upload CSV file'),// '#size' => 40, '#description' => t('This will not work for a non-CSV file.'),// '#required' => TRUE, TODO: breaks it. why?);$form[$form_id]['submit'] = array( '#type' => 'submit', '#value' => t('Submit'),);$form['#attributes'] = array('enctype' => 'multipart/form-data');\[/code\]On a Drupal support site, someone says that it's impossible to make file uploads required. Is this true?