Luks Nuke doesn't work.

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

Code:

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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#

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What i can do? i really need Luks in my laptop.

Did you encrypt your hard drive first using LVM when installing Kali Linux? You need to have an encrypted hard drive first before Luks Patch can work