Problems with Results of the genetic algorithm

[Alvaro]

Good to all friends, I would like you to help me solve a small problem, it happens that when optimizing for maximum balance in metatrader 5 using a genetic algorithm, a simple expert advisor with just a few indicators and activating the forward period with one year out of the sample, after finishing the optimization and giving me the results both in the back test and in the forward test, I select one of the results whose net profit is positive and does not lose money in the back test table and then through the option "Results in Forward Test "I look for it in the Froward table and I observe that in that out-of-sample period the net profit is also positive and neither does it lose money, however at the time of starting the simulation to see the statistics and the balance graph, I observe that in the back test report the net profit, the profit factor, the expected profit coincide with the back testing optimization results table but in the forward testing the statistics do not coincide at all with the forward testing optimization results table and the net benefit is negative since the forward results showed that it was positive; and this makes the platform doubt because it is showing erroneous results.

What is the reason why this happens? If it is assumed that the parameters that I optimize in the in-sample period, I should simply test them unchanged in the out-of-sample period and show the results as they are

Has the same thing happened to someone else?

Greetings