You either got an error because your IMEI is invalid,
your Service Provider was not selected or you did not agree to the terms
and conditions checkbox above the Generate Button.
Your IMEI may be invalid because it has been tampered
with; or repairs and extra parts may have set your IMEI to
another number. Your IMEI must not include and slashes, or
any other characters apart from numbers, This is very
important. There is not bypass method to generate your codes
if your IMEI is invalid.
Yes, All Unlocking codes are different, that's why you must make sure everything is Exact, otherwise it will not work.
Please do not use the same code for one phone