I'm getting a 'No mountable filesystem' after running xpwntool on a dmg for a iPhone 2G (3.1.2). The command I'm running is below. I thought maybe I messed up the keys, but I double checked them and they are correct. What am I doing wrong?

Thanks!

bash-3.2# ./xpwntool 018-6136-014.dmg decrypted_ramdisk.dmg –iv 0e128e1f69806afc476b73250908d641 -k 6a4db11073eb748bad1fabafb066fe13