weird error: "score is not a valid member of IntValue", what does this mean?

trying to make a score leaderboard and I get this error i modified a kills and death leaderboard online, so thats how i got this code.

game.Players.PlayerAdded:connect(function(plr)

     local leaderstats = Instance.new("IntValue",plr)   
     leaderstats.Name = "leaderstats" -- dont change the name or else it will not work!

     local Death = Instance.new("IntValue")
     Death.Name =  script.DeathsName.Value -- The Value with be in the script

     local Kills = Instance.new("IntValue")
     Kills.Name = script.KillsName.Value -- The Value with be in the script
     local score = Instance.new("IntValue")
    score.Name = "Score"
    score.Parent = leaderstats
    plr.leaderstats.score.Value = Kills * 10 - Death * 5
end)

may someone help me with this code?