i actually dont know what i was talking about. let me re-explain. everytime i do a birail surface, the surface couldnt be selected. everytime i click on the surface, instead of picking up the surface, i pick up the isoparm thingy.

another one :
everytime i start a birail operation and i click the wrong curve, i dont know how to restart the operation from scratch. pushing escape button doesnt work. it seems to me maya keep watching what i am doing; so if i do something on a curve, all of a sudden a surface pop out of nowhere. so i think i have to find a way to cancel the birail operation in order to prevent that from happening.

as of this time, i have to restart maya everytime i finish doing birail surface.