[packet listener for forge 1.8.9 doesn't work]

Thank you for your interest in helping me. Do you know another forum where I could post my problem at?

 

[packet listener for forge 1.8.9 doesn't work]

Greetings, I am currently trying to register a packet listener for forge 1.8.9 like this:
 

public class NameChangePacketListener {
    @SubscribeEvent
    @SideOnly(Side.CLIENT)
    public void onPacketReceived(FMLNetworkEvent.ClientCustomPacketEvent event) throws IOException {
        System.out.println("test");
        

        if (event.packet.toS3FPackets() instanceof S38PacketPlayerListItem) {
            S38PacketPlayerListItem packet = (S38PacketPlayerListItem) event.packet.toS3FPackets();

            if (packet.func_179768_b() == S38PacketPlayerListItem.Action.UPDATE_DISPLAY_NAME) {
                for (S38PacketPlayerListItem.AddPlayerData playerData : packet.func_179767_a()) {
                    String newName = playerData.getDisplayName().getUnformattedText();

                    IChatComponent chatComponent = new ChatComponentText("Your name has been changed")
                            .setChatStyle(new ChatStyle().setColor(EnumChatFormatting.GREEN));
                    Minecraft.getMinecraft().thePlayer.addChatMessage(chatComponent);
                }
            }
        }
    }
}

Now, in the init method, I register this listener to the event bus like so:
 

@Mod.EventHandler
    @SideOnly(Side.CLIENT)
    public static void init(FMLInitializationEvent event){
        MinecraftForge.EVENT_BUS.register(new NameChangePacketListener());
    }

I know for a fact the init method works, so why does the "onPacketReceived" method not get called? the "test" doesn't print at all