Sample cBot Reference SMA

hi,

i try to add a simple sma to my bot. so i copy the example in my bot

      [Parameter("Source")]
        public DataSeries Source { get; set; }
        [Parameter("SMA Period", DefaultValue = 14)]
        public int SmaPeriod { get; set; }

        private SampleSMA sma;
        protected override void OnStart()
        {
            sma = Indicators.GetIndicator<SampleSMA>(Source, SmaPeriod);
        }

Error CS0246: The type or namespace name 'SampleSMA' could not be found (are you missing a using directive or an assembly reference?)

i open a new bot, replace the code with the example i have the same error.

can someone explain why code from example is building and same code in new bot is not compiling?

thank you!