Splitting Geometry

 From:  karter
Hi group,

I would like to be able to split a curve or surface edge without the need for making additional geometry......heres what I mean :-

1) Draw a horizontal line 100 units long or whatever you want
2) Run trim & select line
3) Add trim points
4) Input thru keyboard or [D] 20 units
5) Click and hold mouse to make c.line - x,tan (Notice MoI has x marked that position for you as End point)
6) Click on that point
7) Click done

Nothing happens and the curve remains as it was ?? Somebody tell me what im doing wrong please :-))