Check out the errors at the rejects column. If you see “Results of filter formula not defined on calculation date” you will need to load more records. You can find the required amount of data for each system in the manual. Of course this depends on market conditions as well. The Short systems will produce very few trades in a bull market and the bullish system fewer trades in a bear market.
You should therefore run the explorations on as many stocks as possible. If you are an active trader or if your stock list contains less than 500 stocks you should try the BFB,RS or BFC systems which usually produce > 20 trades per day in a bull market.