Occurs when the workflow has errors and can not control the quality. According to the specifications. Because they can not foresee the exact cause. Found in the work: "Yes, but that is not"
Occurs when the process worked, there was an error until it can no longer control the quality to meet the requirements because they cannot know the actual cause of the peoples of. Found in a "thought, Yes, but not"
This happens when the process of working with the error that they could not be able to comply with the requirements for Quality Control because they were not able to appreciate the real reason can be found in the work, "I think that Yes, but it's not."