HTTP 400 (BadRequest) How to solve?

The first version of Assault Criminals, https://web.roblox.com/games/5657867373/Assault-Criminals, is almost ready! But there's a big flaw. The Start Game script is not working. Here's my code:

local TeleportService = game:GetService("TeleportService")
script.Parent.MouseButton1Click:Connect(function()
    local Player = script.Parent.Parent.Parent.Parent.Parent
    local Players = game.Players
    local Server = TeleportService:ReserveServer(game.ReplicatedStorage.PlayerStats[Player.Name].SlotUsing.Value.MissionPlaceId.Value)
TeleportService:TeleportToPrivateServer(script.Parent.Parent.Parent.Missions.Slot1.MissionPlaceId.Value, Server, {game.Players[script.Parent.Parent.PlayersVal.HostName.Value], game.Players[script.Parent.Parent.PlayersVal.Player1Name.Value], game.Players[script.Parent.Parent.PlayersVal.Player2Name.Value], game.Players[script.Parent.Parent.PlayersVal.Player3Name.Value]})
    game.ReplicatedStorage.PlayerStats[Player.Name].SlotUsing.Value.Visible = false
end)

The Error happens on Line 5. How do I fix it? Please follow my game as it is almost ready!