Question about MT4 backtest

Hello,
I am trying to understand how the MT4 tester is working.

- When I am using the Optimizer and I have set several parameters to be optimized why do I see 3 numbers for the progress instead of 2? For example I see 23 / 1280 (1600)? I expect to see 23 / 1600. What is 1280 here?

- After the optimizer finishes I do not see even the results of 1280 passes. I see only the results of 320. "Skip uselss results" is unchecked so I see also passes with negative profit. In Journal tab I see message "optimization stopped, 768 cache records were used, 768 cache records rejected". But I haven't run the optimizer with similar parameters before and the code of the EA is now different anyway. What does this mean?

- What can be the reason to get a different profit when I run a single test compared to the profit which is shown for the pass with same parameters when using the Optimizer?

Thanks in advance

The first number 23 is a progress number. It's at test 23 of a possible 1280 runs.

The second number is based on an algorithm that has determined using parameters you've selected, it should be able to optimize the strategy in 1280 passes or less (thus saving you time) of a possible 1680 passes.

Uncheck "Genetic Algorithm" and you will only see two numbers at the start. Instead of seeing 0/1280(1680), you will see 0/1680.

A stop after 320 tests means it's optimized the system in 320 runs. Any further passes are not enhancing the results.

Thanks
Another question.
Why MT4 shows a maximal drawdown of 8522 for the following system?
(See the attachment)

I do not see drawdown for more than 2000 neither for the Balance, nor for the Equity?