CentOS 7 - Kolab install fails with brocken packages

[Dr. Hirn]

Hi,

discovered that yum is really trying to install el6 packages:
e.g. --> Processing Dependency: kolab-webadmin for package: 
kolab-3.1.9-3.4.el6.kolab_3.4.noarch

So you have been right.
Just couldn't find out, why.

But

> yum  clean all

did the job.

Thank you all for your help!

Stefan