Not able to run command inside plugin

Code:
PLUGIN = nil

function Initialize(Plugin)
	Plugin:SetName("VanillaFill")
	Plugin:SetVersion(1)

	-- Hooks

	PLUGIN = Plugin -- NOTE: only needed if you want OnDisable() to use GetName() or something like that

	-- Command Bindings
	cPluginManager.BindCommand("/setblock", "vanillafill.setblock", setblock, " ~ Changes a block at X Y Z.");
--	cPluginManager.BindCommand("/fill", "vanillafill.fill", fill, " ~ Fills an area from X Y Z to X2 Y2 Z2.");

	LOG("Initialised " .. Plugin:GetName() .. " v." .. Plugin:GetVersion())
	return true
end

function OnDisable()
	LOG(PLUGIN:GetName() .. " is shutting down...")
end

-- This segment is a bit of stripped-down code from the WorldEdit Plugin (github.com/cuberite/WorldEdit)

-- Returns the block type (and block meta) from a string. This can be something like "1", "1:0", "stone" and "stone:0".
-- If a string with a percentage sign is given it will take the second half of the string (With "40%1:0" it uses only "1:0")
function GetBlockTypeMeta(a_BlockString)
	g_DefaultMetas = {
	[E_BLOCK_CHEST]              = 2,
	[E_BLOCK_ENDER_CHEST]        = 2,
	[E_BLOCK_FURNACE]            = 2,
	[E_BLOCK_LADDER]             = 2,
	[E_BLOCK_LIT_FURNACE]        = 2,
	[E_BLOCK_NETHER_PORTAL]      = 1,
	[E_BLOCK_TORCH]              = 1,
	[E_BLOCK_TRAPPED_CHEST]      = 2,
	[E_BLOCK_REDSTONE_TORCH_ON]  = 1,
	[E_BLOCK_REDSTONE_TORCH_OFF] = 1,
	[E_BLOCK_WALLSIGN]           = 2,
	[E_BLOCK_WALL_BANNER]        = 2
}

	if (a_BlockString:find("%%")) then
		local ItemInfo = StringSplit(a_BlockString, "%")
		if (#ItemInfo ~= 2) then
			return false
		end

		a_BlockString = ItemInfo[2]
	end

	local BlockID = tonumber(a_BlockString)

	-- Check if it was a normal number
	if (BlockID) then
		return BlockID, g_DefaultMetas[BlockID] or 0, true
	end

	-- Check for block meta
	local HasMeta = string.find(a_BlockString, ":")

	-- Check if it was a name.
	local Item = cItem()
	if (not StringToItem(a_BlockString, Item)) then
		return false
	else
		if (HasMeta or (Item.m_ItemDamage ~= 0)) then
			return Item.m_ItemType, Item.m_ItemDamage
		else
			return Item.m_ItemType, g_DefaultMetas[Item.m_ItemType] or 0, true
		end
	end
end


function setblock(Split, Player)
	if (#Split ~= 5) then
		-- There was more or less than four arguments (excluding the "/explode" bit)
		-- Send the proper usage to the player and exit
		Player:SendMessage("Usage: /setblock X Y Z [blocktype]")
		return true
	end

    outVector3 = Vector3i(tonumber(Split[2]), tonumber(Split[3]), tonumber(Split[4]))
    Player:SendMessage("Setting block " .. Split[2] .. " "  .. Split[3] .. " " .. Split[4] .. " to type " .. Split[5])
    local type, meta = GetBlockTypeMeta(Split[5])
    Player:GetWorld():SetBlock(outVector3, type, meta)

    return true
end