Yeah, you need to up your kdr, mine is at 96 now, but I need to do high rounds, I'm still at skull with blue eyes. Your kdr is worked out by your kills divided by your downs, not deaths, I heard you need at least 70 kdr for skull and knife. It's slow, but safe, if you wanna raise your kdr, do custom games, town, easy, starting round 15, pack a punch your starting pistol, wipe out the first wave normally, then after buy jugg, then go near the bank so your in line with the stamina up machine. Don't open the bank door, you'll make good trains around this area, if you get cornered or looks like your about to go down, just press start and leave the game, that way all your kills will add to your total and you won't have any downs, just repeat till you get the kdr your after, hope this helps.