Page Chapter 2. Writing a Module, Page 13

Location on the page: 
if ($may_cache)
Error: 

In order to view the menu in admin/settings/annotate, I had to change this line of code:
if ($may_cache)

Correction: 

if (!$may_cache)

I tested this out with the code from this website, and I have the same problem that the menu will not show in admin/settings.

[Using !$may_cache is helpful for development. But the problem you are seeing is outlined in the blog post here. -JV]