I am getting the same error with a RemoteFunction Please help me understand it?

I have been getting this error with a RemoteFunction, I am sending back a table of Player Usernames when It gets called for a ServerInvoke on my Client.

OnServerInvoke is a callback member of RemoteFunction; you can only set the callback value, get is not available

This is an example of my code:

Server:

local WinnerTable = game:GetService("ReplicatedStorage"):WaitForChild("QEvents"):WaitForChild("Winner"):WaitForChild("WinnerTable")
local winners = {"Roblox"}

WinnerTable.OnServerInvoke:Connect(function()
	return winners 
end)

Client:

local WinnerTable = game:GetService("ReplicatedStorage"):WaitForChild("QEvents"):WaitForChild("Winner"):WaitForChild("WinnerTable")
local winners = WinnerTable:InvokeServer()
	for i,v in ipairs(winners) do
		winners = winners + 1
	end

Here's a very simple one it will Damage the player by 10 damage upon spawning:

local script

RF = game.Lighting.RemoteFunction
local player = game.Players.LocalPlayer
local char = player.CharacterAdded:wait()
local result = RF:InvokeServer(char.Humanoid)
char.Humanoid:TakeDamage(result)

ServerScript

RF = game.Lighting.RemoteFunction
RF.OnServerInvoke = function(Player,Received) --First Info is always the Player
	print(Received) 	-- Shows that I've sent over a value from the client side
	Damage = 10
	return Damage
end

RF is the remotefunction's remote, that I've placed inside lighting.