Terrain control mob spawning

Hello im trying to spawn some giants and blazes in the jungle and dessert biome but for some reason they dont spawn during day or night time i type this in the config Its correct according to the JSON Validator (http://jsonlint.com)
I wrote this in the config => spawnMonsters: [{"mob": "giant", "weight": 10, "min": 4, "max": 4}]
Im not using multiverse.

Plugins

1. Bpermissions
2. Backup
3. Citizens
4. Essentials
5. factions
6. Heroes
7. Izone
8. world edit
9. titan chat
10. NcBukkitLib
11. ( dont know what that is lol)
12. Super spawn

I cant delete heroes or factions so if it is this that is causing this problem is there a way around it?

I also changed my essentials config to true for blaze and other mobs and my spawnmoblimit is at 10

 

Is Essentials limiting the spawning, or is some other plugin?

 

Plugin list.