which tutorial/guide did you use ?
and if you want to get better answer than this, plz try to explain entirely what's wrong with your unit.
***make it clear, i'm NOT upset, or mad or anything else....***
btw, don't think that the "Original" Mirage Tank is needed. It adds micromanagment for nothing (a tree isn't that bad since there's always lots of trees in maps). Concerning the spy, it's
normal that you can choose its disguise since it uses opponent's infantry (not a terrain object) as a model, yet you could still play with only a default disguise like the AI do...
