Chess Poem 15: Problem 387 (Limerick) Poem by Kim Barney

This problem is from the book 606 Puzzles for Chess Nuts, by Fred Wilson and Bruce Alberston, Sterling Publishing Company,2008. White supposedly wins by sacrificing his queen for the pawn on a7. Black can't capture with his king because of the white knight covering that square, so he captures the queen with his knight. The white knight then moves to square b6 with check, and the king can only move to b8. The knight then takes the black rook with check, followed by capturing the queen. Since White now has a three-pawn advantage, the endgame should be easy for him to win. Yes, it will take a little time. The game is not over yet. The problem is, there is a flaw in the solution. Who can tell me why it does not work? $100 to the first solver, according to my 'Contest Rules'.