My Exp on Kill and Over time script wont work?

So i have a Leaderstat Called "Exp" but in the scripts its "EXP" im not sure if that matters but, The Exp on kill script doesnt work at all? Any help?

Exp on kill script:

game.Players.PlayerAdded:connect(function(player)
 local folder = Instance.new("Folder",player)
 folder.Name = "leaderstats"
 local currency1 = Instance.new("IntValue",folder)
 currency1.Name = "EXP"
 player.CharacterAdded:connect(function(character)
  character:WaitForChild("Humanoid").Died:connect(function()
  local tag = character.Humanoid:FindFirstChild("creator")
   if tag ~= nil then
    if tag.Value ~= nil then
     currency1.Value = currency1.Value + 300
    end
   end
  end)
 end)
end)

I also want a Exp over time script (for all players in the server) but my current script wouldnt work.

Exp over time script:

amount = 5
timedelay = 0.5
currencyname = "EXP"

while true do
 wait(timedelay)
 for i,v in pairs(game.Players:GetPlayers()) do
  if v:FindFirstChild("leaderstats") then
   v.leaderstats[currencyname].Value = v.leaderstats[currencyname]. Value + amount
  end
 end
end