When I install a plugin in Eclipse everything goes well. But after restarting the new plugin is not visible. I have tried it with different plugins, but they have all the same problem. The only place where I can see them is when I look at "What is already installed?".
What could be the problem?
This issue and its solution is described in a DZone article and at the nWire blog.
It all boils down to these two options: