In Black Ops Call Of the Dead how do you get the golden rod(in co-op mode)?

I think you are looking at the wrong cave. I have found this blue looking ice-wall near the spawn, to the left of the quick revive, it has a design on it and what looks to be an arrow, try to shoot it with the V-R11 and the Scavenger, I'm not sure which works, if it does work. It is supposed to break and reveal a cave and in it is the golden rod, try this out, I haven't gotten to it as my friends and I fail at getting the Scavenger/V-R11 :/. The gun might have to be upgraded as well.