I did many tests on Z1 & Z2 with default settings ,mostly the result is just likc the samples in the manual, more or less. But I still get some very bad result one or two times.Why?Is it a bug?

Why, that's a good result. Not many commercial strategies come even close.

Do not stare only at the annual return: it's mostly random. Ulcer index, Sharpe ratio, and profit factor are more important. Read the "Performance report" chapter about the meaning of the performance values, and their limits.

The result is really good actually, but my point is the tests use "same defult settings" but turn out "a far different result", so I wonder maybe there is a bug in test function?

I'v lost the "normal" report, but I remember the AR is more then 300%, just like the one in the manual, and this report shows 81%. 81% is good,but why?