Entities will spawn on the client but not on the server

For some reason my entities spawn fine on the client but on a server they don't spawn properly. On my servers they spawn normally in a small radius around the spawn but as I move away they stop spawning. I register my entities with:

EntityRegistry.addSpawn(EntityZombieDayZ.class, 200, 1, 4, EnumCreatureType.creature, DayZ.dayzForest, DayZ.dayzPlains, DayZ.dayzRiver);

Anyone have an idea why this is occurring?