Problem KDE4

[Andreas Scherf]

Hello,
since upgrading my 8.04 Kubuntu to 9.04 the plasmaengineexplorer did not show 
any systemmonitor sources. 
The problem is that some plasma widgets did not work. Is there a package 
mssing on my system or are some settings wired? Other plasma channels work 
properly. Upgrading to KDE 4.3 Beta did not help here is the same problem.
I also googled the problem but did not find an answer.

Could anybody help me?

Regards
Andreas