Two Rook mate challenge #1 Cannot figure out mistake

Yes. There are some mistakes in their puzzles.
One IM.. one time ... he confirmed that.
But the most of the puzzles are very good.
Yes. There are some mistakes in their puzzles.
One IM.. one time ... he confirmed that.
But the most of the puzzles are very good.
https://www.chess.com/endgames/checkmates/two-rooks-mate/challenge
Playing this challenge I perform a 2 move mate with Rook to A7 followed by Rook to h8, however the puzzle is giving me a red cross, how can this possibly be wrong as it is the fastest mate possible?