stroke subpath with smudge tool

hi everyone, I have very simple question, but somehow I can't get an issue. my problem is, when I'm trying to stroke a path with smudge tool, it works fine until I select simulate pressure in dialog box. it's strange because I saw it working fine. my friend use all the time. the only difference is he uses a macintosh and I use a windows. but as I see it, there is no way that different OS can be a reason for a problem.
if somebody know, please help me
thx ahead, vasya

I assume you are using a tablet, that is another variable to consider. Perhaps it is not set up correctly.

yes, I checked it with brush tool, it works perfect

In Window>Brushes in brushes tab click on the word "other dynamics" and see if "Control" is off or on Pen Pressure. Also, check help files under pressure if that is not it.