It means you are not using the latest version of the Battlecode release (version 0.0.3). Make sure you have downloaded the newest release and run "ant update" (or Update Battlecode).
Your lib folder should contain the battlecode-2016.0.0.3.jar file, and none of the older versions. Make sure to
ant clean (or delete your
bin directory) before you try compiling.
We made an API change to ZombieSpawnSchedule.