[Zope] Product doesn't appear in Add List

Hi, I'm a beginner of Zope. I read Documentation(ZCMG) and trying to create a sample Zope Product, just the same thing as in that tutorial. I did as follows: 1. create Product Distribution Archive (tgz file) in Distribution tab. 2. delete original one (with open-box icon). 3. shutdown zope. 4. re-install it (by extracting tgz in zope directory). 5. restart zope. As a result, it appears in Control_Panel/Products directory (with normal close-box icon), but doesn't appear in the 'Available Objects' Add List. I didn't forget to create factory object. I'm using Zope 2.1.6. Please help. Thanks.