Boring Pips MT4 V4.1 NO DLL

The most likely answer is Over-fitting. Many EAs are created to ‘learn’ and adapt perfectly to the available historical data, but they fail to predict the future due to a lack of generalizability in the constructed model. Some developers simply don't know about the existence of over-fitting, or they know but don't have a way to prevent it. Others exploit it as a tool to beautify their backtest results, they add dozens of input parameters without considering statistical significance, making the trading strategy excessively tailored to historical data and attempting to convince others that their EA can achieve similar performance in the future. If you are interested in this fascinating subject and want to get a deeper insight into over-fitting, please refer to my articles here:   There are several ways to avoid losing money on an expert advisor whose only ‘edge’ is reading past data, and the easiest way is NEVER TO USE AN EXPERT ADVISOR WITHOUT LIVE TRADING RESULTS FOR AT LEAST 5 MONTHS