Forum:More Ken combo nonsense

Forgive me if the following is irritating to anyone...

While attempting/succeeding at doing the "Ken combo" (fair, fair, dair for the spike) with Marth, I've noticed that it's extremely easy for the other player to escape. That is to say, while mid-combo, the player is often able to jump out or air parry after one or two hits. My hypothesis is that I'm not doing it fast enough in order for it to take effect, but is it just a combo that's easily escapable for anyone who knows how to jump or air parry? Also, can anyone send me in the direction of some decent beginner combos or theory for Marth?

Things I DON'T NEED to be reminded of:
 * the dair spike hit can only be a tipper in order for it to work