CMS Made Simple Forums

Hello

I'm working on my first module, and trying to display error messages in my tabs. I have 2 tabs in my module, where I show the result of the database query.

If the query was succesfull, I use:
$params = array('tab_message' => 'succes', 'active_tab' => 'mylist');
$this->Redirect($id, 'defaultadmin', $returnid, $params);

If the query fails, I use:
$params = array('tab_message' => 'fail', 'active_tab' => 'mylist');
$this->Redirect($id, 'defaultadmin', $returnid, $params);

But I want a red frame, and not a green when it fails. I found out that I can show a red frame with ShowErrors(); but I can't get it working.

Can someone get me on track?