whenevr i extrude a polyline a message "appears one selected curve rejected" i think this is the problem in Icad u cannot extrude polyline

This happens to me often, but it's a matter of making sure all the polyline segments are "connected" and in the same plane. I find that if I explode it and slowly add sides or arc segments using PEDIT it will work. You can do "list" on it to see if it is open or closed.