Why will this FE script give me a nil value when played?

I have this FE script that goes nil when it is played. This is the error 20:42:48.509 - Players.powerdud.PlayerGui.LocalScript:2: attempt to index local 'XP' (a nil value) I don't understand why this doesn't work. If someone could help me it would be much appreciated.This is my code

Server script

game.Players.PlayerAdded:connect(function() 
    local Data = Instance.new("IntValue") 
    Data.Parent = script.Parent.Parent
    Data.Name = "Data" 
    local XP = Instance.new("IntValue") 
XP.Parent = script.Parent.Parent
    XP.Name = "XP" 
    XP.Value = 0
    local Level = Instance.new("IntValue") 
Level.Parent = script.Parent.Parent
    Level.Name = "Level"
    Level.Value = 1 
    local Tries = Instance.new("IntValue")
Tries.Parent = script.Parent.Parent
    Tries.Value = 10
    Tries.Name = "Tries"
    local ExCap = Instance.new("IntValue")
ExCap.Parent = script.Parent.Parent
    ExCap.Value = 500
    ExCap.Name = "ExCap"
    XP.Changed:connect(function() XP.Value,Level.Value,ExCap.Value) end)
end)



function XPChange(XP.Value,Level.Value,ExCap.Value)
    game.Workspace.RemoteEvent:FireClient(ExCap,Level,XP)
    end 

Basically XP is changed it will fire a Event called FireClient

Local script

game.Workspace.RemoteEvent.OnClientEvent:Connect(function(ExCap.Value,Level.Value,XP.Values)
        if XP.Value >= ExCap.Value then
        if Level.Value < 100 then
            Level.Value = Level.Value + 1;
            XP.Value = XP.Value-ExCap.Value;
            ExCap.Value = ExCap.Value * 2;
        end
    end
    if Level.Value == 100 and XP.Value ~= 0 then
        XP.Value = 0;
end
end)

When XP rises more than ExCap, XP will subtract from ExCap

It's because OnClientEvent doesn't really take player parameter, so do this instead on line 2:

game.Workspace.RemoteEvent.OnClientEvent:Connect(function(ExCap,Level,XP) --just remove the Player parameter you had there

Dont send like value objects to client, instead send their real values, so instead of sending XP, Level and ExCap send their values so XP.Value and same for other.

In your local script you can have everything the same just again don't compare XP.Value but instead compare just XP

Also Instance.new with parent argument is deprecated and ineffective so you should set a parent of an object after you set all properties, also it's Connect instead of connect.