post_count maxes out at 13

I am trying to show post_count in a search box with a hierarchical dropdown menu. The problem I am having is the post_count for the parent category is maxed out at 13 but I have many more posts than that.

Here is the code I am using to generate the dropdown:

<?php wp_dropdown_categories('show_count=1&hierarchical=1&exclude_tree=1,3,4,6,7,8,34,113,234,235&orderby=name'); ?>

Where is the hang-up? I can not figure this out and I am sure it is something simple.

Also, is there a way to I can ‘include’ categories instead of ‘exclude’ them in the ‘exclude_tree’ so that each time I add a cetegory I don’t have to go back and modify my exclude_tree?

Thanks for any input or direction.