[answered]unable to cast instance to int64?

I set up a remote event to handle purchases for my game because it makes me feel neater and I'm getting "unable to cast instance to int64" in the dev console the script causing this error is: and the error occurs on line 7 and line 23

local MPService = game:GetService("MarketplaceService")
local HttpService = game:GetService("HttpService")
local Webhook = "empty because one of the reasons im using a remote event is security"
local event = game.ReplicatedStorage.hey

event.OnServerEvent:Connect(function(player, assetId)
    promptpurchase(player, assetId)
end)

function GetSales(assetId)
    local data = HttpService:JSONDecode(HttpService:GetAsync("https://api.roblox.com/Marketplace/ProductInfo?assetId="..assetId))
    local sales = data.Sales
    return(sales)
end

function GetName(assetId)
    local data = HttpService:JSONDecode(HttpService:GetAsync("https://api.roblox.com/Marketplace/ProductInfo?assetId="..assetId))
    local name = data.Name
    return(name)
end

function promptpurchase(player, assetId)
    MPService:PromptPurchase(player, assetId)
    MPService.PromptPurchaseFinished:connect(function(Player, assetID, isPurchased)
        if isPurchased then
            local HookData = {
            ['username'] = "shop",
            ['content'] = "Player: "..player.Name.."\nAsset Bought: "..assetId"
            }
            HookData = HttpService:JSONEncode(HookData)
            HttpService:PostAsync(Webhook, HookData)
        end
    end)
end

I've literally tried every possible thing I could think of, but lua's a very confusing language to me sometimes with the errors I get.

anyone got any ideas?

edit: some of you asked for what i was inputting as params so here it is:

game.ReplicatedStorage.hey:FireServer(game.Players.LocalPlayer, 320412452)