spell with onTargetTile

[Paulix]

hello, recently im working on this old spell of my server

local acombat = createCombatObject()

local combat = createCombatObject()
setCombatParam(combat, COMBAT_PARAM_TYPE, COMBAT_PHYSICALDAMAGE)
setCombatParam(combat, COMBAT_PARAM_BLOCKARMOR, 1)
setCombatParam(combat, COMBAT_PARAM_DISTANCEEFFECT, CONST_ANI_POWERBOLT)
setCombatParam(combat, COMBAT_PARAM_EFFECT, CONST_ME_HITAREA)
setCombatFormula(combat, COMBAT_FORMULA_LEVELMAGIC, -3.8, -220, -3.8, 220)

local arr = {
{1, 1, 1},
{1, 1, 1},
{1, 1, 1},
{0, 1, 0},
{0, 3, 0}
}

local area = createCombatArea(arr)
setCombatArea(acombat, area)

function onTargetTile(cid, pos)
   doCombat(cid,combat,positionToVariant(pos))
end

setCombatCallback(acombat, CALLBACK_PARAM_TARGETTILE, "onTargetTile")

function onCastSpell(cid, var)
   return doCombat(cid, acombat, var)
end

as you can see its working pretty well, the only problem is that the effect hits instantly, while the bolts take a couple frames to reach its destination... i would like to know how exactly this function on target tile works, and if there is any way to make it only show the HITAREA effect once bolt reaches his destination...