Why don't birds like my new feeder?

I have had a very successful squirrel proof peanut feeder for a number of years. Just before the dreadful weather started I put up another squirrel proof feeder nearby this time for bird cake and sat smugly back - apart from a few pecks, a month later it remains untouched. The peanut feeder remains popular and I change/defrost the birdbath daily. Unfortunately because of strange garden configuration I can't see the garden from the house so don't know who visits the peanut feeder. We have lot of magpies who "live" two gardens along - could they be the problem?