@ArmBoy Make sure you have an icon for it being On and Off.
9c593e99-3a34-42be-9c14-23d7a6add8e3-image.png
Check if Unit and Aura Type is correct on both.
aa50883f-f736-4bdd-8fbc-be506cf5c2dd-image.png
Make sure you are setting Show On, set to Aura Missing and don't use "Show if Unit does not exist", as shown here.
0637e30c-5683-4c52-b1dd-e893f7e801f6-image.png
It works for me with this setup.
Hope this helps.