my crystal ball shows the OP is running the AutoIt script with elevated permissions, and that script needs to run another process not elevated. there are several ways to do that, one of which is the _RunWithReducedPrivileges which works just fine for me.
then again, my crystal ball may be broken... ah, if only there was a way to make the OP describe his purpose more clearly. i'm certain there is a simple way to achieve whatever purpose he has in mind.