Hooking widget on tag cloud doesn't work

Hi,

my site has a sidebar with a tag cloud and other widgets. I had make a hook to set a container around the widgets and it works. But not with the tag cloud. This is my code in functions.php in the theme folder:

if ( function_exists('register_sidebar') )
register_sidebar(array(
'name' => 'Linke Spalte, ohne Überschrift',
'before_widget' => '<div class="leftsmallwidget">' ,
'after_widget' => '</div></div><div class="container_footer_block"></div></div>',
'before_title' => '<div class="container_headline_block"><h3>',
'after_title' => '</h3></div><div class="container_body_block"><div class="btext">',
));

Is there any setting I forgot?

Thanks for your help and sorry for my bad english 😉
Dominik