are you saying that the brown rinse says that the base is red & gold? if that's the case i don't know why you are getting a the results you are. i would be careful to use a red base, because you can end up with a pink hue. i would go for a gold base. grey hair is missing warmth.
The same also holds true on blond hair when I lowlight it with a non ammonia color. I wouldn't put anything in the brown color except a gold base. It's comes out to the most natural looking brown.