[Mobhack]

They should not (yet) be on the map if they are reinforcements. That message comes up if the weapon or unit index is out of bounds, or you have hit a target which has the reinforcement turn set to >0, ie it's a reinforcement unit not yet on the map (supposedly).

As Don says - a save game would be most useful here, to debug this, or a note of the scenario number if this is a scenario game.

Cheers
Andy