How to use the .setharvestlevel 1.7.10

i have tried to use .sethervest level but it says can not convert void to block heres the code:

package com.raze.blocks;

import java.util.Random;

import com.raze.item.*;

import com.raze.main.*;

import com.raze.lib.*;

import net.minecraft.block.Block;

import net.minecraft.src.*;

import net.minecraft.world.World;

import net.minecraft.block.material.Material;

import net.minecraft.creativetab.CreativeTabs;

import net.minecraft.entity.item.EntityItem;

import net.minecraft.init.Blocks;

import net.minecraft.init.Items;

import net.minecraft.item.Item;

import net.minecraft.item.ItemStack;

import net.minecraftforge.common.MinecraftForge;

import cpw.mods.fml.common.registry.GameRegistry;

import cpw.mods.fml.common.functions.*;

public class Mods_CarbonOre {

public static void mainRegistry(){

initializeBlock();

registerItem();

}

public static Block CarOre;

public static void initializeBlock(){

CarOre = new CarOre(Material.rock)

.setBlockName("CarOre")

.setCreativeTab(CreativeTabs.tabBlock)

.setBlockTextureName(RefStrings.MODID + ":CarOre")

.setHardness(3)

.setResistance(15);

.setHarvestLevel("pickaxe", 1);

}

public static void registerItem(){

GameRegistry.registerBlock(CarOre, CarOre.getUnlocalizedName());

    }

}