Error when update SDK

When I update SDK by SDK -> help -> check for updates , I got this Error:
network problem

Not all the plugins have been succesfully dowloaded. The server may be unavailable at the moment. Try again later.

I try to update the SDK because my project contains files with errors. I need to reinstall the SDK?

I don’t know it’s solved or not. I post the solution I did to: http://hub.jmonkeyengine.org/forum/topic/the-problem-with-junit-and-with-running-of-the-project-in-debug-mode/#post-210095