Cannot parse custom emoji string into Emoji object

await socketMessage.AddReactionAsync(Emoji.Parse(":Goatcutie:"));

System.FormatException: String is not emoji name or unicode!
   at Discord.Emoji.Parse(String emojiStr)
   at Goatbot.Modules.Goats.OnMessageAsync(SocketMessage socketMessage) in D:\code\Goatbot\GoatBot\Modules\Goats.cs:line 26
   at Discord.EventExtensions.InvokeAsync[T](AsyncEvent`1 eventHandler, T arg)
   at Discord.WebSocket.DiscordSocketClient.TimeoutWrap(String name, Func`1 action)