This is not to say that the interrogation program has worked perfectly. According to the IG Report, the CIA, at least initially, could not always distinguish detainees who had information but were successfully resisting interrogation from those who did not actually have the information. See IG Report at 83–85. On at least one occasion, this may have resulted in what might be deemed in retrospect to have been the unnecessary use of enhanced techniques. On that occasion, although the on-scene interrogation team judged Zubaydah to be compliant, elements within CIA Headquarters still believed he was withholding information. See id at 84. At the direction of CIA Headquarters, interrogators therefore used the waterboard one more time on Zubaydah.