can't use psvn

[step]

 hi guy:

     now i use the gnu emacs23.0.0 , download the latest version
psvn.el from http://www.xsteve.at/prg/index.html.
     then add the line (require 'psvn) to my .emacs file . when i M-x
svn-status ,and type in the directory which is svn project dir. but
i get the error message
   "and: Wrong type argument: number-or-marker-p, nil"
   *svn-status* buffer not appear,other svn command also has the some
error. what's the mistake?
 can anybody tell me about this ? thanks all
    my system is debian