Adding an image banner to a node created by my module

Hi,

I am writing a module which will create a new content type (through code, not CCK). Everything is fully working except when I am trying to add a banner at the bottom of the page:

function mymodule_view($node, $teaser = FALSE, $page = FALSE) {

    if (!$teaser) {
      // Use Drupal's default node view.
      $node = node_prepare($node, $teaser);

      $node->content['banner'] = array(
        '#value' => "<img src='aaaa.gif' />",
        '#weight' => 10
      );

    }
    if ($teaser) {
      $node = node_prepare($node, $teaser);
    }
    return $node;
}

Ignore for the moment that I am not using themeable function for generating the image. Also not that in my module the image src is not aaaa.gif (I wrote it here only to simplfy the code). I know for sure that the image exist and I link to it but it won't appear (is there some sort of filtering??).
However when I add a text (instead of images) it appears:

      // This works fine
      $node->content['banner'] = array(
        '#value' => "SOME TEXT HERE",
        '#weight' => 10
      );

      // nothing happens here
      $node->content['banner'] = array(
        '#value' => "<img src='aaaa.gif' />",
        '#weight' => 10
      );

Is there any way to fix that ?

Thank a lot,
Fadi