CentOS 7 - Kolab install fails with brocken packages

[Dr. Hirn]

Hi Andrea, hi Brian,

> It looks like you are pointing at the wrong repo. Yum is trying to
> load el6 files which are for centos 6. You need el7 files.

I double checked the repos before writing to the list. I'm absolutely 
sure, I used the right ones.

Followed the guide Andrea has written (thanks for that!). Didn't change 
anything.

# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
  * base: mirror.nextlayer.at
  * epel: ftp.upjs.sk
  * extras: mirror.nextlayer.at
  * updates: mirror.nextlayer.at
repo id - repo name - status
Kolab_3.4 - Kolab:Development (CentOS_7) - 370
Kolab_3.4_Updates - Updates for Kolab 3.4 (CentOS_7) - 237
base/7/x86_64 - CentOS-7-Base - 8,652
epel/x86_64 - Extra Packages for Enterprise Linux 7 - x86_64 - 8,308
extras/7/x86_64 - CentOS-7 - Extras - 149
updates/7/x86_64 - CentOS-7 - Updates - 995
repolist: 18,711

Do you have any other ideas?

Thx
Stefan