Help with Anti-Jump script?

function noHelmet(chr)



    local s = script.NoHelmet:clone()

    s.Disabled = false

    s.Parent = chr



end



function checkHelmets()

    local p = game.Players:GetPlayers()



    for i=1,#p do

        local c = p[i].Character

        if (c ~= nil) then 

            local helmet = c:findFirstChild("Space Hat")

            if (helmet == nil and c:findFirstChild("NoHelmet") == nil) then

                noHelmet(c)

            end

        end

    end

end



function makeLowGrav(Head)

    print("NoJump", Head)

    local b = Instance.new("BodyForce")

    b.Name = "NoJump"

    b.force = Vector3.new(0,-20000,0) --adds a new body force. this will stop you from going up. try to go up, it will push you back down again!

    b.Parent = Head

end



function onPlayerRespawn(property, player)



    if property == "Character" and player.Character ~= nil then

        makeLowGrav(player.Character.Head)      

    end

end









function onPlayerEntered(newPlayer)

        while true do

            if newPlayer.Character ~= nil then break end

            wait(5)

        end

        newPlayer.Changed:connect(function(property) onPlayerRespawn(property, newPlayer) end )



        makeLowGrav(newPlayer.Character.Head)   

end





game.Players.ChildAdded:connect(onPlayerEntered)











while(true) do

    wait(3)

    checkHelmets()

end

It still lets the player jump.

Could anyone fix it so you cannot jump at all?