Can I possibly use a fire server instead of invoke server?

MY PICKAXE SCRIPT -- it says 21:16:01.128 - ServerScriptService.MainScript:51: attempt to index field '?' (a nil value) 21:16:01.129 - Stack Begin 21:16:01.129 - Script 'Players.Theevilem.Backpack.Pickaxe.PickaxeScript', Line 11 21:16:01.130 - Stack End

HERE IS THE CODE

local Debounce = true
script.Parent.Activated:connect(function()
    if Debounce then
        Debounce = false
        local Ore
        if game:GetService("UserInputService").MouseEnabled then
            local Mouse = game.Players.LocalPlayer:GetMouse()
            Ore = Mouse.Target
        end
        if Ore and Ore.Parent == workspace.Mine then
            game.ReplicatedStorage.MineOre:InvokeServer(Ore)
        end
    end
    wait(0.3)
    Debounce = true
end)

MY MAIN SCRIPT -- It says 21:16:01.678 - ServerScriptService.MainScript:51: attempt to index field '?' (a nil value) 21:16:01.679 - Stack Begin 21:16:01.679 - Script 'ServerScriptService.MainScript', Line 51 21:16:01.680 - Stack End

HERE IS CODE

game.Players.PlayerAdded:connect(function(Player)
    Player.CharacterAdded:connect(function(Character)
        repeat wait() until Character:FindFirstChild("Torso")
        Character.Torso.CFrame = CFrame.new(0,5050,0)
    end)
end)

local UsedPositions = {}
local function PositionKey(x,y,z)
    return x..","..y..","..z
end

local function GetOreFromId(Id)
    for i,Ore in pairs(game.ReplicatedStorage.Ores:GetChildren()) do
        if Ore.Id.Value == Id then
            return Ore
        end
    end
end

local function Gamble(y)
    local Lottery = {}
    for _,Ore in pairs(game.ReplicatedStorage.Ores:GetChildren()) do
        local MaxDepth, MinDepth = (Ore.MaxDepth.Value > 0 and Ore.MaxDepth.Value) or 9999, (Ore.MinDepth.Value > 0 and Ore.MinDepth.Value) or 1
        local Range = MaxDepth - MinDepth
        local MinDistance = y - MinDepth
        local MaxDistance = MaxDepth - y
        local MaxRarity, MinRarity = Ore.MaxRarity.Value, Ore.MinRarity.Value
        local Chance = math.ceil(((MinDistance/Range) * MinRarity + (MaxDistance/Range) * MaxRarity) / 2)
        for i=1,Chance do
            table.insert(Lottery,Ore.Id.Value)
        end
    end
    local Id = Lottery[math.random(1,#Lottery)]
    return GetOreFromId(Id)
end

local function GenerateOre(x,y,z) 
    if UsedPositions[PositionKey(x,y,z)] == nil and y > 0 then
        local Ore = Gamble(y):Clone()
        Ore.Parent = workspace.Mine
        Ore.Position = Vector3.new(0 + x*6,5000 + y*(-6),0 + z*6)
        UsedPositions[PositionKey(x,y,z)] = true
    end
end

function game.ReplicatedStorage.MineOre.OnServerInvoke(Player,Ore)
    local CompactPos = Vector3.new(0 + Ore.Position.X/6,(Ore.Position.Y - 5000)/(-6),Ore.Position.Z/6)

    _G["PlayerData"][Player.Name]["Inventory"][Ore.Name] = _G["PlayerData"][Player.Name]["Inventory"][Ore.Name] + 1
    game.ReplicatedStorage.InventoryChange:FireServer(Player, _G["PlayerData"][Player.Name])

    for x=1,3 do
        for y=1,3 do
            for z=1,3 do
                if CompactPos.Y + (y-2) > 1 then
                    GenerateOre(CompactPos.X + (x-2),CompactPos.Y + (y-2),CompactPos.Z + (z-2))
                end
            end
        end
    end
    Ore:Destroy()
end

math.random(os.time())

for x=1,26 do
    for z=1,26 do
        GenerateOre(x,1,z)
    end
end

THANK YOU