Hi, i got this problem today and i can't solve it, i was searching on the internet but nothing:

Code:
root@kali:/dev# cryptsetup luksAddNuke /dev/sda
Device /dev/sda is not a valid LUKS device.
root@kali:/dev# cryptsetup luksAddNuke /dev/sda1
Device /dev/sda1 is not a valid LUKS device.
root@kali:/dev# cryptsetup luksAddNuke /dev/sda2
Device /dev/sda2 is not a valid LUKS device.
root@kali:/dev# cryptsetup luksAddNuke /dev/sda5
Device /dev/sda5 is not a valid LUKS device.
root@kali:/dev# ls | grep sda
sda
sda1
sda2
sda5
root@kali:/dev# cat /proc/partitions
major minor  #blocks  name

   8        0  488386584 sda
   8        1  480232448 sda1
   8        2          1 sda2
   8        5    8151040 sda5
  11        0    1048575 sr0
root@kali:/dev#
What i can do? i really need Luks in my laptop.