[1.7.10] Not all of my custom ores are spawning

/**
* This class was created by <Professorvennie>. It's distributed as
* part of the Machinery Craft Mod. Get the Source Code in github:
* https://github.com/Professorvennie/MachineryCraft
*
* Machinery Craft is Open Source and distributed under a
* Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License
* (http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB)
* */
package com.professorvennie.core.world;

import java.util.Random;

import com.professorvennie.core.block.ModBlocks;

import com.professorvennie.core.main.handlers.ConfigHandler;
import net.minecraft.block.Block;
import net.minecraft.item.ItemStack;
import net.minecraft.world.World;
import net.minecraft.world.chunk.IChunkProvider;
import net.minecraft.world.gen.feature.WorldGenMinable;
import cpw.mods.fml.common.IWorldGenerator;

public class OreGen implements IWorldGenerator {

private ItemStack copperOre = new ItemStack(ModBlocks.BlockOres, 1, 0 );
private ItemStack tinOre = new ItemStack(ModBlocks.BlockOres, 1, 1);
private ItemStack silverOre = new ItemStack(ModBlocks.BlockOres, 1, 2);
private ItemStack leadOre = new ItemStack(ModBlocks.BlockOres, 1, 3);
    private ItemStack zincOre = new ItemStack(ModBlocks.BlockOres, 1, 4);

@Override
public void generate(Random random, int chunkX, int chunkZ, World world, IChunkProvider chunkGenerator, IChunkProvider chunkProvider) {

	switch(world.provider.dimensionId){
		case -1: generateNether(world, random, chunkX * 16 , chunkZ * 16);
		case 0: generateSurface(world, random, chunkX * 16 , chunkZ * 16);
		case 11: generateEnd(world, random, chunkX * 16 , chunkZ * 16);
	}
}

private void generateEnd(World world, Random random, int x, int z) {

}

private void generateSurface(World world, Random random, int x, int z) {
        if(ConfigHandler.spawnCopper)
            addOreSpawn(Block.getBlockFromItem(new ItemStack(ModBlocks.BlockOres, 1, 0 ).getItem()), world, random, x, z, 16, 16,ConfigHandler.copperVienSize, ConfigHandler.copperRate, 15, 160);
        if(ConfigHandler.spawnTin)
            addOreSpawn(Block.getBlockFromItem(new ItemStack(ModBlocks.BlockOres, 1, 1 ).getItem()), world, random, x, z, 16, 16,ConfigHandler.tinVienSize, ConfigHandler.tinRate, 15, 160);
        if(ConfigHandler.spawnSilver)
            addOreSpawn(Block.getBlockFromItem(new ItemStack(ModBlocks.BlockOres, 1, 2 ).getItem()), world, random, x, z, 16, 16,ConfigHandler.silverVienSize, ConfigHandler.silverRate, 15, 160);
        if(ConfigHandler.spawnLead)
            addOreSpawn(Block.getBlockFromItem(new ItemStack(ModBlocks.BlockOres, 1, 3 ).getItem()), world, random, x, z, 16, 16,ConfigHandler.leadVienSize, ConfigHandler.leadRate, 15, 160);
        if(ConfigHandler.spawnZinc)
            addOreSpawn(Block.getBlockFromItem(new ItemStack(ModBlocks.BlockOres, 1, 4 ).getItem()), world, random, x, z, 16, 16,ConfigHandler.zincVienSize, ConfigHandler.zincRate, 15, 160);
    }

private void generateNether(World world, Random random, int x, int z) {
        
    }

    /**
* Adds an Ore Spawn to Minecraft. Simply register all Ores to spawn with this method in your Generation method in your IWorldGeneration extending Class
*
* @param The Block to spawn
* @param The World to spawn in
* @param A Random object for retrieving random positions within the world to spawn the Block
* @param An int for passing the X-Coordinate for the Generation method
* @param An int for passing the Z-Coordinate for the Generation method
* @param An int for setting the maximum X-Coordinate values for spawning on the X-Axis on a Per-Chunk basis
* @param An int for setting the maximum Z-Coordinate values for spawning on the Z-Axis on a Per-Chunk basis
* @param An int for setting the maximum size of a vein
* @param An int for the Number of chances available for the Block to spawn per-chunk
* @param An int for the minimum Y-Coordinate height at which this block may spawn
* @param An int for the maximum Y-Coordinate height at which this block may spawn
**/
public void addOreSpawn(Block block, World world, Random random, int blockXPos, int blockZPos, int maxX, int maxZ, int maxVeinSize, int chancesToSpawn, int minY, int maxY)
{
      int maxPossY = minY + (maxY - 1);
      assert maxY > minY: "The maximum Y must be greater than the Minimum Y";
      assert maxX > 0 && maxX <= 16: "addOreSpawn: The Maximum X must be greater than 0 and less than 16";
      assert minY > 0: "addOreSpawn: The Minimum Y must be greater than 0";
      assert maxY < 256 && maxY > 0: "addOreSpawn: The Maximum Y must be less than 256 but greater than 0";
      assert maxZ > 0 && maxZ <= 16: "addOreSpawn: The Maximum Z must be greater than 0 and less than 16";
     
      int diffBtwnMinMaxY = maxY - minY;
      for(int x = 0; x < chancesToSpawn; x++){
             int posX = blockXPos + random.nextInt(maxX);
             int posY = minY + random.nextInt(diffBtwnMinMaxY);
             int posZ = blockZPos + random.nextInt(maxZ);
             (new WorldGenMinable(block, maxVeinSize)).generate(world, random, posX, posY, posZ);
      }
}

}