Pocket Wizard trouble
Are the Speedlights fully recycled?Sometimes you shoot at close to or at full power and the AA's take time to recycle. You shoot a shot, try and shoot another at 2 seconds, while it needs four to fully recycle.
If waiting 5 seconds or longer before shooting shot to shot, make sure flash or camera is not going to sleep.
If recycle time or sleep time is not a problem, suspect the Pocket Wizards