So this is the layout it is a big cube with just cobblestone then there about and eight by eight corners for mobs to spawn and in the middle of those has a stream of water to wash them down a 2 by 2 hole. It is about 24-28 blocks in the air. The hole down below the huge mob grinder cube has it incased in another cube of cobblestone so no stray light can come in. My problem is that no monsters are spawn and it is confusing why because it is literally pitch black in there but none are spawning I hope this helped

Hmm... judging by that, I don't think there's anything wrong in that. If the floor for the mob grinder is entirely made of stone slabs, especially the mob spawners, that would interrupt the spawning process.

I think you should refer to Gamepedia for further details of this.

https://minecraft.gamepedia.com/Tutorials/Mob_grinder#Minecraft_Pocket_Edition_Mob_Grinders

The only thing I could think is that it is in the sky so that makes the mobs not load possibly but not sure honestly. 

Ah, there's the problem. Make sure you build the thing just lower so it could at least be rendered.

Most likely the reason it doesn't work is related to you being to far away from the spawning area. And you need to hang around there for the mobs to spawn.

This is a major difference related to the Java edition, you (or other players) need to be close enough for the grinder to work. The optimal range you'll need to experience with, but 24 I think is a little high. On Java you do have some spawn chunks which makes having mob grinders somewhat easier (especially when you're not around).

In 1.2 you'll also get the tickingarea option which you can use to trigger the mob grinder to spawn even when you're not around.(That is if I've understood that option correctly)

Oh ok thank you for both of your help I just wish I find this out before remodling it to see if it worked because I want to do it all on survival no creative at all thank you again!!!

I guess I mistook it. Thanks for clarifying, Holroy.