Datastore not saving values?

I'm trying to make a datastore for a game but it's giving me some trouble. I'm pretty new to datastore, I made this script and have been working on it for a while but I still can't seem to fix it. Any Idea's as to why is not working?

Server Script in ServerScriptService:

local DSS = game:GetService("DataStoreService")
local RepStorage = game:GetService("ReplicatedStorage")
local saveData = RepStorage.saveData
local RedlinePlayerDS = DSS:GetDataStore("RedLineRacing[Datastore]")
local Tutorial = RepStorage.TutorialEvent

SessionData = {}

local PlayerDataTemplate = {
    --["Name"] = {"ValueType"},
    ["Rowg Coins"] = {"NumberValue", 15000},
    ["Miles Driven"] = {"NumberValue", 0},
    ["Rank"] = {"StringValue", "Permit"},
    ["Ae86"] = {"BoolValue", false},
    ["180SX"] = {"BoolValue", false},
    ["1968 Challenger"] = {"BoolValue", false},
    ["911"] = {"BoolValue", false},
    ["Accord"] = {"BoolValue", false},
    ["Camaro SS"] = {"BoolValue", false},
    ["Corvette Z06"] = {"BoolValue", false},
    ["Huracan Performante"] = {"BoolValue", false},
    ["LFA"] = {"BoolValue", false},
    ["Lancer Evolution"] = {"BoolValue", false},
    ["Miata"] = {"BoolValue", false},
    ["ModelS"] = {"BoolValue", false},
    ["Senna"] = {"BoolValue", false},
    ["Supra"] = {"BoolValue", false}
}

game.Players.PlayerAdded:Connect(function(player)
    --Variables
    local playerKey = "player_"..player.UserId
    local CarStorage = Instance.new("Folder", player)
    CarStorage.Name = "OwnedCars"
    local leaderstats = Instance.new("Folder",player)
    leaderstats.Name = "leaderstats"

    --simple generic-for loop to make new value instances:
    for name, object in pairs(PlayerDataTemplate) do
        local newValue = Instance.new(object[1])
        newValue.Name = name
        newValue.Value = object[2]

        if object[1] == "NumberValue" or object[1] == "StringValue" then
            newValue.Parent = leaderstats
        else
            newValue.Parent = CarStorage
        end
    end

    local GetSave;
    local success, message = pcall(function()
        GetSave = RedlinePlayerDS:GetAsync(playerKey)
    end)

    if success then
        --DataStore worked and retrieved something. We continue.
        if GetSave then
            SessionData[playerKey] = GetSave
            for _, object in ipairs(CarStorage:GetChildren()) do
                if object:IsA("BoolValue") then
                    print(object.Name, GetSave[object.Name])
                    object.Value = GetSave[object.Name]
                end
            end
            for _, object in ipairs(leaderstats:GetChildren()) do
                if object:IsA("StringValue") or object:IsA("NumberValue") then
                    print(object.Name, GetSave[object.Name])
                    object.Value = GetSave[object.Name]
                end
            end
            print("Data loaded for "..player.Name)
        else
            print("Welcome "..player.Name.." To RedLine Racing!")
            SessionData[playerKey] = {
                ["Rowg Coins"] = 15000;
                 ["Miles Driven"] = 0;
                 Rank = "Permit";
                Cars = {
                    ["Ae86"] = false;
                    ["180SX"] = false;
                    ["1968 Challenger"] = false;
                    ["911"] = false;
                    ["Accord"] = false;
                    ["Camaro SS"] = false;
                    ["Corvette Z06"] = false;
                    ["Huracan Performante"] = false;
                    ["LFA"] = false;
                    ["Lancer Evolution"] = false;
                    ["Miata"] = false;
                    ["ModelS"] = false;
                    ["Senna"] = false;
                    ["Supra"] = false;
                    }
            }
        end
    else
        warn("Can't Load Player Data! Reload Server.")
    end
end)

game.Players.PlayerRemoving:Connect(function(player)
    print(player.Name.." Has Left!")
    local playerKey = "player_"..player.UserId
    local CarStorage = player.OwnedCars
    local leaderstats = player.leaderstats
    local GetSave = RedlinePlayerDS:GetAsync(playerKey)

    for _, object in ipairs(CarStorage:GetChildren()) do
                if object:IsA("BoolValue") then
                    SessionData[playerKey].Cars.object.Name = object.Value
                end
            end
            for _, object in ipairs(leaderstats:GetChildren()) do
                if object:IsA("StringValue") or object:IsA("NumberValue") then
                    SessionData[playerKey].object.Name = object.Value
                end
            end

    local success, message = pcall(function()
        RedlinePlayerDS:SetAsync(playerKey, SessionData[playerKey])
    end)

    if success then
        print("saved success for "..player.Name)
    else
        warn("Did not save because: "..message)
    end
end)