Trying to Model the All Ordinaries and S&P 500

I tried applying the same model I am using for trading the NASDAQ 100 to the All Ordinaries and S&P 500. The results were very poor for the All Ordinaries - buy and hold performed better, while for the S&P 500 the model might add value but better results can be obtained by trading SPX using the trade directions generated by the NDX. I'm not surprised about the All Ordinaries as it is driven to such an extent by what happens in the US markets. Much of each day's move typically occurs overnight Australian time while the US market is open. The stochastic is rather noisy and hard to model. Recently, there has been much less noise... I think the S&P 500 is just not volatile enough relative to the NASDAQ. This is why I started trading the NASDAQ. In future work I might try modeling more than one index simultaneously. I expect there are gains to be had from that.