I'm not a Canon expert, and you could likely get a faster response over at the Strobist flicker group... thousands of people there use your setup successfully.
I have no idea of your level of understanding or experience and you forgot to mention WHAT kinds of PWs you are using (PWII's or the newer ones that support eTTL, the Flex and mini versions).
Either way... ask here:
http://www.flickr.com/groups/strobist/ (sorry typed so fast that initially I gave you a wrong link! This is the good one)
You will likely get an answer within minutes.
I am adding to this post, but wanted you to see this part... more is coming in a few seconds.
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Added info:
If you are using the Pocket Wizard II's (PW II's), which do NOT support eTTL, you still have some minor setup to do;
- make sure that both transceivers are on the same channel
- that the first one is mounted into the hotshoe of your camera and that the transmit mode switch is set to BOTH
- that the second one is hung to the side of your light stand and that the transmit mode switch is set to BOTH as well. There is a wire that sends the transmit signal from the receiver to your flash in one of 2 manners, either by connecting the wire that exits the FLASH socket from the PW to a hot-sync connector on your flash, or, if your flash doesn't have one, that your flash is sitting in a hotshoe connector that has a sync port in it and your PW connects to this connector.
- You will have to set your flash to a fully manual mode (refer to your manual for this) and set the power to something low like 1/4 power for testing purposes.
- Press the TEST button on the PW that the flash is connected to, if it fires the flash, thats a good sign.
- Press the TEST button on the PW that is sitting in the hotshoe of your camera, if it fires the flash, thats a good sign.
- Take a test shot, it should work.
This is about as far as I (a Nikon user) can help you assuming you have PW II's and not the newer units. For more help, refer to the site I mention up above.
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Ah, I missed a hint in my haste to answer... you have the new PWs, the ones that support TTL. My info above is not pertinent to you... sorry. The strobist club is your best bet. I did leave the rest of the info becuase thought it is not pertinent to the new ones, it is a good procedure to follow for users of the "older" non-TTL versions that have been successfully used for years. I will mention something though... there is a lot of talk about the 580 EX II and their noise levels that play havoc with these newer versions of the PWs. I do hope that you, as a professional, have backup solutions to your shoot tomorrow, or if it is not on a professional level and no backups, can reschedule the event without any inconvenience to anyone.
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One more piece of info... a good place to ask questions directly to PW and people that use the new PWs:
http://www.flickr.com/groups/pocketwizards/
Good luck!