Yes. The server is on Normal difficulty with mobs set as enabled. There is no land near the spawner, although I'm not sure about the caves. But even if I didn't know about possible caves, the entity count is only at four. And for the floor I used cobblestone spawning pads not packed ice, but why would that matter? No plugins, just regular 1.8.3
I have also changed the platforms to packed ice but still nothing. I've looked up other forum posts similar to this, but I have already done everything that was suggested. If anyone could get back to me on this topic, that would be helpful.