Why is ND key not working?

So i was start in the exploit and click on retrieve key. I did the i not a robot thing right! and i copy and paste the key in the exploit. It said "This authentication key was not generated on this machine Rember you cant share keys! Please generate another one. And the key was off my my pc i had my exploit on. I try again same message. and i keep try and keep happen! Please tell me whats the problem!