Ninjhax error (only me?)

Hi everyone, I'm here to ask about an error that occurs to me when trying to install ninjhax my 3ds is New 3ds (Japan) Firmware: 9.1.0-20J. The installation always stuck at 40% with this message "failed to open sd:/boot.3dsx." c8804478. I already put the boot.3dsx file on the root of my sd card but it keep happenings.

Please help
thx