Module script and Remote Events problem?

Ok, so basically this I'm having a bad time trying to fix this.

I have a Module script called "ServerPlayer" (used in a non-local script in the workspace), which contains a set of functions (ServerPlayer:addPlayerRequest(), ServerPlayer.setStatusRequest()...). I have a RemoteEvent object which the player requests any function of this module. For example, a player could add itself by running "remoteEvent:fireServer('addPlayerRequest',LocalPlayer.Name)". This is my code:

ServerPlayer = require(game.ReplicatedStorage.Classes.Core.ServerPlayer)
local serverPlayer = ServerPlayer.new()

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local remoteEvent = ReplicatedStorage:WaitForChild("RemoteEvent")

function runRequest(player, functionName,...)
    print("Request from player "..player.Name.." received! Function name: "..functionName..". Args:",unpack({...}))

    serverPlayer[functionName](...)
end

remoteEvent.OnServerEvent:Connect(runRequest)

However, for some reason, whenever a player sends a requests from a local script and calls any function, the self clause within the module becomes null for some reason. For example, the module has a property called "LocalData". Whenever a player requests to call the addPlayer function, It prints the following error:

ReplicatedStorage.Classes.Core.ServerPlayer:31: attempt to index nil with 'LocalData'

An exception is returned because of "self.LocalData". However, whenever I call manually this function by writting something like:

serverPlayer:addPlayerRequest("Player1")

It works fine, but when I do It like:

serverPlayer["addPlayerRequest"]("Player1")

The self clause becomes null and the code fails. Any idea of how to fix this? (Sorry for my english)