Mobs aren't spawning in my Minecraft PE Server
Solution 1:
As of April 18, 2015, PocketMine does not support mobs. It does not spawn mobs naturally, you must use a spawn egg, but then it won't move. The developers are working on this feature but until then you will have to wait. PocketMine doesn't spawn anything naturally including all types of mobs, tall grass, and fire**. This applies to all platforms that PocketMine supports.
** Fire doesn't burn the block that it was placed on either.