Troubles checking debuff on raid members

[fatrog]

Hello,

I have made a custom tiny addon just for my personal use. (It helps me getting better with addon making)
My goal is to put a symbol on the 4 players who got the debuff "Controlled Burn" (used by the first boss of the new raid)

But despite what I tried, I can't get it working...

Here is my actual code so far:

local raidTargetIcons = {1, 2, 3, 4}
 
local function UpdateRaidDebuffList()
    for i = 1, GetNumGroupMembers() do
        local unit = "raid" .. i
        for j = 1, 40 do
            local _, _, _, _, _, _, _, _, _, _, spellId, _, _, _, _, _, castSuccess = UnitDebuff(unit, j)
            if not spellId then
                break
            end
 
            if spellId == 421972 and castSuccess then
                local icon = table.remove(raidTargetIcons)
                if icon then
                    print(GetUnitName(unit, true) .. " has successfully cast Controlled Burn.")
                    ApplyRaidTargetIcon(unit, icon)
                end
                break 
            end
        end
    end
end
 
local function ApplyRaidTargetIcon(unit, icon)
    SetRaidTarget(unit, icon)
end
 
local function ClearRaidTargetIcon(unit)
    SetRaidTarget(unit, 0)
end
 
local function OnEvent(_, event, _, sourceGUID, _, _, _, _, _, destGUID, _, _, spellId)
    if event == "COMBAT_LOG_EVENT_UNFILTERED" then
    elseif event == "SPELL_AURA_REMOVED" and spellId == 421972 then
        local destName = GetUnitName(destGUID, true)
        if destName then
            local icon = GetRaidTargetIndex(destName)
            if icon then
                table.insert(raidTargetIcons, icon)
                ClearRaidTargetIcon(destName)
                print(destName .. "'s Controlled Burn debuff has been removed.")
            end
        end
    end
end
 
local frame = CreateFrame("Frame")
frame:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED")
frame:SetScript("OnEvent", OnEvent)