Target Mark For "tornado" Options

[Nosf3ratu]

I'm in the mission where the target marks spell "TORNADO". Well, I can't seem to shoot the first O that you come across. Its the one on top of a ledge in the first area where those 4 VSs come out. I've tried every weapon possible. I've sniped it, laser rifled it, shot it with rockets, gatling gun, machine gun, energy gun, plasma gun, EVERYTHING! But it still remains.