How To Restore Categories Count in Sidebar Widget?

I’m using the Default 1.6 (Kubrick) Theme.

Before I added Sidebar Widget (1.2.1), my categories list included the number of posts in each category alongside each category title in parentheses. Now it doesn’t.

I think it’s something to do with these lines in the Theme’s sidebar.php

</li>
<?php wp_list_categories('show_count=1&title_li=<h2>Categories</h2>'); ?>

The above is how it appeared in the Theme’s original sidebar.php file. In Sidebar Widget’s modified file, it appears like this:

<li><h2>Categories</h2>
<ul>
<?php wp_list_cats('sort_column=name&optioncount=1&hierarchical=0'); ?>
</ul>

I’ve tried modifying Sidebar Widget’s line thus:

<li><h2>Categories</h2>
<ul>
<?php wp_list_cats('show_count=1&sort_column=name&optioncount=1&hierarchical=0'); ?>
</ul>

(i.e. adding show_count=1& to the front of the line, and later I also tried changing wp_list_cats to wp_list_categories) but it makes no difference.

Am I looking in the correct area? Is it possible to restore the count at all in Sidebar Widget?

Thanks in advance for any help.