[cvsnt] history and access right

[zhuyunchuan]

I created a repo and imported a module named ModuleSample, then assigned 
rights to user A and user B as following:
user A:  CVSROOT  rw
          ModuleSample  rw
user B:  CVSROOT  r
           history (file in CVSROOT) rw
          ModuleSample  rw

After user A and user B modified some files and commit them , I use 'cvs 
history' to get the log . I could get the log of user A but not user B. 
Why? How can I pretend the CVSROOT directory and log the history ?