I dont think it's full screen,take your character past sweep distance/half screen away.check.

It worked. They got the distance wrong in the Move List.

yeah move list says half screen away, that is too far away.
http://www.mortalkombatonline.com/content/games/mk3/sektor/
Mods should edit that to say sweep distance. What I do is start at sweep distance , hold block, press forward x 3, back, release block then press block again. Maybe their logic is that if you start from half distance, by the time you press forward 3 times you will be at sweep distance. But that will only happen if you have arthritis while you tap forward x 3.....