Do not worry, this is not your fault.
Sometimes the result is wrong because of the difficulties with the float numbers comparison.
Here is a part of a discussion about that:
Floating point math is not exact. Simple values like 0.2 cannot be precisely represented using binary floating point numbers, and the limited precision of floating point numbers means that slight changes in the order of operations can change the result. Different compilers and CPU architectures store temporary results at different precisions, so results will differ depending on the details of your environment. If you do a calculation and then compare the results against some expected value it is highly unlikely that you will get exactly the result you intended.
The full article is here: http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
This error appears extremely rare in FSB because of the logic:
f1 is higher than f2 when f1 > f2 + point/2
Normally "Previous High Low" has to be used with a technical indicator like MA in the entry slot.
In your strategy the entry point is equal to the bar opening:
[Opening point of the position]
Enter the market at the beginning of the day
Base price - Open
And you use the entry filter:
The position opens below the previous High
In this case the position opens at the "Day Opening" that is equal to "Bar Opening" when this bar is the first one for the current day.
Normally Open Price = Close Price (bar - 1); (when "data refining" is on this is always true)
The logic of the strategy is like this:
"Data refining" - off
Open long at the first price of the day when this price is lower than the previous high (there is no gaps between the bars)
Open short at the first price of the day when this price is higher than the previous low (there is no gaps between the bars)
When "Data refining" - on ( there are no gaps between the bars)
Open long at the first price of the day when the previous bar hasn't got upper shadow
Open short at the first price of the day when the previous bar hasn't got lower shadow
I can assume that the result of your strategy comes from a float numbers comparison bug when FSB compares the open price of the current bar and the previous bar highest price when they are equal each other.