The model and texture/animations all work properly, they show up in the cutscene editor just fine.
I found out this when making doodads: Duplicate a KorhalSkyscraper model (in the Data/Models Tab) and instead of using the default model, switch to Nova or a Siege Tank.
It'll result in the error of the message log spamming you and a sphere showing up.
I would say you probably need an actor to handle the doodad. Make sure the actor is properly linked to the doodad. Check the actor's events and make sure there is a create message somewhere. It's typically applied to a UnitBirth.<YourUnitID> event.