I have seen many topics made, where people are saying that they are going 3 or more rounds on the bridge using only the Hell's Retriever, (trying to get the Redeemer) and not getting their sound cue.
(I think) I have the solution!
Do you have the Zombie Shield on your back? And if so, at any point during any of these rounds, did the Zombies hit it at all? I have done multiple tests with and without the Zombie Shield on the bridge, planting the shield on the bridge, and letting the shield break during my time on the bridge.
I have found that if the Zombies ever hit the shield, it counts as you "using" the Zombie Shield, and won't count the round as using the Retriever only.
If you have the shield on your back, but don't get hit, it will work just fine. If you plant the shield in the corner and the Zombies don't attack it, then it also will work just fine.
Hope this clears up some of the problems some players have been having.
The Self-Proclaimed Master Bard of the Xbox Black Ops 2 Boards. Pope of the Church of MK 48