i create a box then a dish but when i subtract the dish from the box it doesn't work....in using intellicad 4PE+ ang my os is win xp home edition....what seems to be the problem

Welcome to the club. It's a known bug, see my topic "editing extruded solids". We're all waiting for the promised patch.

yeah bro i read your topic that also my prob, added to that even solids can't be subtract
need that patch