[Zope] RAM Cache Manager doesn't work for my script

Hi, all I'm trying to use RAM Cache Manager to cache a Python Script object. The script is pretty simple. Just a call of a SQL Method and some logic. I've made this script cacheable using "Cache" tab, ran this script several time. Then went to "Statistics" tab of Cache Manager. But the cache doesn't work -- I see only zeros opposite my script. What's wrong? How to get the cache working in this case. Any help greatly appreciated. Thanks, -- -tick