whats wrong with that spell

[andu]

sometimes not deals damage

local combat = createCombatObject()
setCombatParam(combat, COMBAT_PARAM_TYPE, COMBAT_PHYSICALDAMAGE)
setCombatFormula(combat, COMBAT_FORMULA_DAMAGE, -1200, 0, -2000, 0)
setCombatParam(combat, COMBAT_PARAM_EFFECT, CONST_ME_GROUNDSHAKER)

local area = createCombatArea(AREA_CIRCLE3X3)
setCombatArea(combat, area)

local function onCastSpell1(parameters)
    doCombat(parameters.cid, combat, parameters.var)
end

function onCastSpell(cid, var)

local parameters = { cid = cid, var = var}
local hp = getCreatureHealth(cid)

if hp <= 1400 then
	addEvent(onCastSpell1, 2000, parameters)
	doCreatureSay(cid, "Demonic Stomp", TALKTYPE_ORANGE_1)
end

return TRUE
end

Can someone fix?