Anytime you are working with third-party add-ons and software installation, something can go wrong. However, using the installation methods described in this chapter will help you ”items will either install or they won't. If the installation fails, a complete error message will be shown, along with links that enable you to quickly search for similar errors or report your bug to Plone developers.
It's important to remember to restart Zope after you add something to the Products directory, in anticipation of installing it. This directory is not read in real time, so if you simply place the program files in the Products directory and navigate to the QuickInstaller (or Plone setup screen), you'll find that these new items are not in the list of available products. Zope must be restarted for these items to appear. However, you do not need to restart Zope after you successfully install a product, nor do you need to log out and log back in again to see changes. If you feel that your screen should be showing different items, reload the page or clear your browser's cache.