Event question: SPELL_CAST_SUCCESS

[indoviet]

Hi I'm a newbie addon developer and I'm running into some trouble understanding the SPELL_CAST_SUCCESS event. I wrote a short block of code that is supposed to detect when a specific spell is casted and then trigger a cooldown frame I set up. However, the event only triggers when the spell casted is an instant cast spell such as Corruption or Drain Soul. When I successfully cast a casted spell like Haunt or Shadow Bolt, the event doesn't trigger.

Can someone help me understand why SPELL_CAST_SUCCESS doesn't work for casted spells and what event I should be using instead?

Here is my code for reference:

function DispelBar_OnEvent(event,...)	
	local timeStamp, event, hideCaster, sourceGUID, sourceName, sourceFlags, sourceRaidFlags, destGUID, destName, destFlags, destRaidFlags = select(1,...)
	
	if(event=="SPELL_CAST_SUCCESS") then
		local spellName = select(13,...)
		print("SPELL_CAST_SUCCESS"..": "..spellName)
		if(spellName == "Haunt") then
			CooldownFrame:SetCooldown(GetTime(), 10)
		end
	end
end

In this example if I changed

if(spellName == "Haunt")

to an instant cast spell like

if(spellName == "Corruption")

then it works.

Thanks for all help in advance and let me know if I need to clarify anything.