Error use functions theme

The theme functions are being used incorrectly. Sample:

  $delimg = theme('image', drupal_get_path('module', 'render') .'/images/delete.png');

Change:

$variables = array();
  $variables['filepath'] = drupal_get_path('module', 'render') .'/images/delete.png';
  $delimg = theme('image', $variables);