[Aftermathhqt]

Hello there, i have a minor problem, i don't know it's not working but i'm trying to do a framefade, with castbars, and it's not working. Any reasons?

local f = CreateFrame('Frame')
            f:RegisterEvent('PLAYER_TARGET_CHANGED')
            f:RegisterEvent('PLAYER_FOCUS_CHANGED')
            f:RegisterEvent("UNIT_SPELLCAST_SENT")
            f:RegisterEvent("UNIT_SPELLCAST_START")
            f:RegisterEvent("UNIT_SPELLCAST_CHANNEL_START")
            f:RegisterEvent("UNIT_SPELLCAST_CHANNEL_STOP")
            f:RegisterEvent("UNIT_SPELLCAST_STOP")
            f:RegisterEvent('UNIT_SPELLCAST_FAILED')
            f:RegisterEvent('UNIT_SPELLCAST_INTERRUPTED')
            f:RegisterEvent('UNIT_SPELLCAST_DELAYED')
            f:RegisterEvent('UNIT_SPELLCAST_CHANNEL_UPDATE')
            f:RegisterEvent('UNIT_SPELLCAST_CHANNEL_INTERRUPTED')
            f:SetScript('OnEvent', function(event)
                    if unit == "player" or unit == "target" or unit == "focus" or unit == "pet" then
                        if self.Castbar then
                            if event == "UNIT_SPELLCAST_START" or event == "UNIT_SPELLCAST_CHANNEL_START" then
                                UIFrameFadeIn(self.Castbar, 0.8, self.Castbar:GetAlpha(), 1)
                            elseif event == "UNIT_SPELLCAST_STOP" or event == "UNIT_SPELLCAST_SENT" or event == "UNIT_SPELLCAST_FAILED" then
                                UIFrameFadeOut(self.Castbar, 0.8, self.Castbar:GetAlpha(), 0.2)
                            end
                        end
                    end 
                end
            end)
        end
    end