I have added a PPA repository to my fresh installation of Ubuntu 12.04 with the Software sources menu item in the Ubuntu Software Center (USC). The problem is that the new repository is not immediately available. I can't find an option to refresh the software sources in the USC. I have tried to close the USC and reopen it, but no success. I don't know if this is a question of time (USC needs some time to refresh?), or if I'm doing something wrong. In the meantime I had to install another software, so I have installed this one. At the end of the installation I have checked out again the software sources, and this time the new PPA repository was there. So, there is some kind of software sources refresh, but I don't know how to force it.
There is somebody else that had this issue?