Can't Desecrate a spectre

I was able to find this monster: https://poedb.tw/us/Slithering_Servant
and raise it as a spectre. However it does not show when I use desecrate.

Monster is found in Vaults of Atziri and you can raise it as a spectre once it's killed. But when I go into my hideout and cast desecrate it doesn't spawn it's corpse.