Native Encryption on Xperia S Missing?

[gregory_opera]

Apparently Android offers native encryption:
Encrypt your phone - Android OS Help

But as per the instructions at the link above, I don't have an "encryption" option in my settings, despite the fact that various sites claim this is a new feature to Android 4.x (my Xperia S runs Android 4.0.4 at the time of writing)...

Any idea as to why I don't have the "encryption" menu option?

 

[sr2012]

Currently not offered so I am using AndroidLost app to protect my phone.

Sent from my LT26i using Android Central Forums