Platformer double jump

Hi. How can I produce a double-jump action in a platformer? I'm using the platform behaivour with the NONE default controls. I set up the action below in the picture which I assumed would work, but it doesn't. Any ideas why? I've seen one method for double-jumps using a variable but it means I'd have to change the jumping method I use atm which I'd rather not do.

Any help appreciated.

<img src="http://img31.imageshack.us/img31/9045/jumphw.jpg" border="0" />

BTW I do know this could result in multiple jumps instead of just two, but I'm toying with using that anyway. I need to test it first when I get it fixed.

i think this can help you...

https://dl.dropbox.com/u/90034817/scirra/doublejump%28smalibary%20edition%29.capx

the controls :

w = jump

a = left

d = right

That worked a treat and without much change to the current method! Thanks very much :)