Please note that after solving the daily puzzle of today, I come to the idea that if white also promotes his pawn into a rook, the solution is still valid; however, the system states that promoting it into a rook is wrong and rather it should be promoted into a queen to get to the solution.
Thanks for reporting this. Yes, sometimes the problems may have more than one solution and in this case it seems that it skipped the testing phase. We will add the rook promotion as an alternative. Thank you very much!