Two 580s - cant get just the slave to fire!!!!

[Ultra]

Ok I have no idea what I could be doing wrong but I just bought two 580ex the other day and tested them on day one, read through the entire instruction manual carefully and everything worked fine.

Today (literally right now) I have the master (attached directly to my 20D) and I have a slave in a softbox setup. I was trying to test shots by having the master off and only have the slave fire (which worked on day 1). Now I cant get it to work :( and its a simple thing to do...

After following the instructions on page 36 of the manual:
"1. Press the <ZOOM/zigzag> button so that the display blinks as shown on the left.
2. Disable the master unit's flash firing.
Turn the <dial> to select <o FF>, then press the <centerdial> button
The <zigzag> icon will blink"

The master still fires I've confirmed that the settings are correct because the little zigzag symbol is blinking and the 3 lines coming from the flash are now gone.

Any thoughts on what I could be doing wrong or what settings I may have on the camera that may be causing this?

I've swapped both unit and changes the settings correctly yet they BOTH still fire... driving myself nuts because I got it to work before!!!

[PacAce]

Yes, the master will still fire. That's the preflash and the command pulse you see. But it won't fire when the exposure is actually made. Did you actually try taking a picture and checking the result?

[Lotto]

The steps you took to turn off the master is right on. Unfortunately the master 580 will fire no mater what mode/setting it's on.

The way Canon slave flash works is like this: the slave flash's firing is triggered by pulse flash (or command flash) from the master unit, not IR like the ST-E2, but actual flash. So if we want the slave 580 to fire during the openning of the shutter, the master 580 must fires the command flash after the shutter opens. In ETTL mode, the master 580 will fire the preflash before the shutter opens, then the command flash right after the shutter opens, and finally the "real" flash (in your case, no flash).

The command flash does not affect the final exposure, unless you are using iso 1600, f1.4, and very close to the subject.

[Ultra]

Wow and I thought I was going crazy... I would have bet some money the first time I did it that the master didnt fire, oh well... I did notice what you guys are saying and noticed in the test shot there is slight illumination from the master when it is off.

Here were my results...

p.s. excuse the quality and composition of the pics... I was doing some rough testing :)

thanks for the responses.