Why will :FireServer() not work?

Ok, so im trying to make a game where a leaderstat value (food) goes up every second based on the FPS value.

it used to work on my old clicker game, but now it does not :( so i tried making it intro a fire server system like my click button, but for some reason it does not work

Code: (using a normal Script)

--cpsadd

while true do
	game.ReplicatedStorage.SecondEvent:FireServer()
	wait(1)
end

Previous Code:

--cpsadd
plr = script.Parent.Parent.Parent
CPS = plr.leaderstats.extrafps
CPS2 = plr.leaderstats.FPS
CPS3 = plr.leaderstats.Boost2

while true do
	plr.leaderstats.Food.Value = plr.leaderstats.Food.Value + CPS2.Value
	plr.leaderstats.Food.Value = plr.leaderstats.Food.Value + CPS.Value
	plr.leaderstats.Total_Food.Value = plr.leaderstats.Total_Food.Value + CPS.Value
	plr.leaderstats.Total_Food.Value = plr.leaderstats.Total_Food.Value + CPS2.Value
	plr.leaderstats.Food.Value = plr.leaderstats.Food.Value + CPS3.Value
	plr.leaderstats.Total_Food.Value = plr.leaderstats.Total_Food.Value + CPS3.Value
	print("give fps")
	wait(1)
end

Previous code also using local script

Function FireServer can only be called from the client.

In order to send messages from Client to server, you need to use the FireServer Function on a local script and OnServerEvent Event on the server side.

Example:

Local script

local RE=game:GetService('ReplicatedStorage'):WaitForChild('RemoteEvent');
RE:FireServer('wow FE');

Server Script

local RE_1=Instance.new('RemoteEvent',game:GetService('ReplicatedStorage'));
RE_1.OnServerEvent:Connect(function(pl,a)
	print(tostring(a));--> 'wow FE'
end);