Hmm...you can definitely create sprites of units using ICE, and I wonder if this is the same...for example the Siege Tank base unit creates the turret using the Iscript, but the turret is a normal unit itself. Still, this has to do with the Subunit property :/ I wonder what will happen if you remove the Turret as the subunit for ST, but leave the Iscript untouched, will it work?