skull system

[Crixpx]

hello all some can help me? i need conver this script to tfs 1.2 can help me? srry for my bad englishs:
this is the creaturescript

local storage = 2533
function onKill(cid, target)
    local frags = getPlayerStorageValue(cid, storage)
    if(isPlayer(target)) then
        setPlayerStorageValue(cid, storage, frags+1)
        if(frags < 10) then
            doCreatureSetSkullType(cid, SKULL_GREEN)
        elseif(frags < 20) then
            doCreatureSetSkullType(cid, SKULL_WHITE)
        elseif(frags < 30) then
            doCreatureSetSkullType(cid, SKULL_RED)
        elseif(frags > 39) then
            doCreatureSetSkullType(cid, SKULL_BLACK)
        end
    end
    return true
end