The tricky part here is making sure you are in the right directory with your command. If you aren't sure go back and look where the output file is for Mission 8. Since 9 is very similar go through and manually direct yourself to the directory your command is written to go. If it's in the wrong place for the file then you need to make adjustments.
"The quieter you become, the more you are able to hear..."
"Drink all the booze, hack all the things."