That is a question I always heard from my student, who took his exam and failed. There are a lot of conditions that impacted your exam, let me explain to you:
1- You did exactly my workbook, but that is your feeling, I don't believe that.
I could not say that I don't believe your knowledge, just only a problem we are human and we always made mistake, even a minor mistake could kill you in the exam. As I said many times, CCIE is a fucking game with a lot of problems, if you missed a command Cisco will cost you so much. That is why you need to keep track your practicing and send your running configuration to Combat and CC Dreamer, who could help you to check and find out your problem:
I recommend you read that article from my student, who passed his exam a long time ago: https://cciers.ccie4career.com/news/detail?id=44
And he mentioned: Send also your configs to Combat or CC Dreamer for validation.
you will see a problem with a candidate, who said with me: he did exactly my workbook but when I checked on him, that is what I saw.
2- You removed some pre-configured in your exam:
There are a lot of pre-configured in your exam, as I said many times: Don't remove if it not impacted your LAB. Many guys never pay attention to that problem, he saw it differently in the lab that practiced at home and removed, at that time Cisco kill you because they know that you are a dumper and don't understand about the whole lab.