The issue here is that the drive was partitioned with the lvm member hex code. So thats where your error is coming from. You dont mount an LVM mount point by the physical device name, i.e., /dev/sda2
You will mount it with the lvm device name as shown in your lvdisplay above. Now in all honesty it looks like your drive is already mounted and apart of the vg_luke volume group.
Do a "pvdisplay" and it should show your actual device name, /dev/sda2, mapped to the volume group.