During the installation I setup LVM for / (boot is on separate partition). The system boots an works without any problem, but if I start yast lvm it behaves like there's no lvm present and tries to create new volume groups etc. Therefore I'm unable to work with the real LVm setup (resizing, ...)

PS. I'm not skilled lvm user so please tell me what logs/setting etc. should I attach to describe it better.

I changed nothing related to lvm since the installation.

fstab:
/dev/system/sl10.1-root /       reiserfs        acl,user_xattr 1 1
/dev/sda5       /boot   ext2    acl,user_xattr 1 2
/dev/sda1       swap    swap    defaults 0 0
proc    /proc   proc    defaults 0 0
sysfs   /sys    sysfs   noauto 0 0
usbfs   /proc/bus/usb   usbfs   noauto 0 0
devpts  /dev/pts        devpts  mode=0620,gid=5 0 0

But in yast partition manager there's different information for root:
device: /dev/dm-0
Type: DM
Mount: /