Harry Potter and the Half Blood Prince

HELP........i have downloaded Harry Potter and the Half Blood Prince for the DS, when i turn the game on it says "no save data found please turn off and reinsert the DS card. What am i doing wrong? ???

What brand of card are you using?
miros

I've got a M3 DS Simply card

You need to update your firmware :) It is covered in the Common Issues https://www.romulation.org/forum/index.php?topic=1462.0 If you already have the latest firmware, ARM7 patch it.