I typed "do you have a dragon" and it said it was wrong. The "correct" answer is "have you a dragon." Does that mean something?
It should have accepted that. Duo is sometimes picky about capitals and punctuation, although it is not supposed to make a difference. If it happens again, please report the problem on the 'Duolingo troubleshooting duscussion', where it will come to the attention of the Duo staff who can fix system-level problems.