I've just installed KDE on Ubuntu. But after installing it ubuntu software center is not installing or removing any softwares. It is giving a output something like this
Authentication Error
Software can't be installed or removed because the authentication service is not available. (org.freedesktop.PolicyKit.Error.Failed: ('system-bus-name', {'name': ':1.184'}): org.debian.apt.install-or-remove-packages
One think I need to tell you that when I am switching to Unity software center is working fine but when I am switching back to KDE it is not working. please help me :'( I've installed the package and tried the instruction but it didn't work. I also tried to use Kubuntu software center but it is not working too :(

polkit-kde-1help you? (sudo apt-get install polkit-kde-1and restart the software centre). And are you using the Software Centre from KDE (Muon Software Centre) or the Unity (regular) one inside a KDE session? Please edit your question to provide this information. – gertvdijk Jan 27 at 18:21