[Zope] Product installation problem

Hi, I have just installed Zope with pcgi to Apache. Everything seems to work fine except when I un-tared example products into lib/python/products and restarted Zope, they are not loaded at all. Alternatively, when I put the new Products into /usr/lib/python1.5/site-packages/Zope/Products, I can see the new Products loaded into the control panel/product management screen but I cannot get the newly installed products to work. They appear on the control panel/product management but nothing is added to the pull-down "add" menu. Anyone know what I may be doing wrong? thanks in advance, Andrew Ho