unable to install and active package

Hello, dear all:
When I install and active a package through wm web page, no responding message appeared like package asdf has been actived successfully.
And i found the error log is :wm.server.packages:packageInstall java.lang.NullPointerException.
No matter it is a new package or a package has already been there.
Please help.
What is the reason and how can i deal with it except restart the server which may help?
Many thanks


Does this happen on all packages or just some packages? Are you sure that the ZIP file you are trying to install is, in fact, an IS package? What happens when you create a new package with a single service, export that package to a ZIP file, delete it from IS and then try to install it again from the ZIP file using Administrator?