When the EOS 1D X and 5D Mark III were introduced, they proved to be incompatible with the PocketWizard MiniTT1 and FlexTT5 radio flash control units. Pocket Wizard has been working to resolve the problem and now has firmware updates for the units.
You will find the update for the EOS 5D Mark III at:
http://www.pocketwizard.com/support/downloads/
The firmware for the EOS 1D X is still in beta, but you can download it at:
http://www.pocketwizard.com/support/downloads/beta
You will find the update for the EOS 5D Mark III at:
http://www.pocketwizard.com/support/downloads/
The firmware for the EOS 1D X is still in beta, but you can download it at:
http://www.pocketwizard.com/support/downloads/beta