apache with windows mapped drive

OS is windows xp, apache is apache 2.2.

on my windows xp, i have a mapped driver, path is \dev3, under dev3 i have a folder www\project.

now i have added following virtual host to my local apache conf file.

ServerName project.localhost

DocumentRoot "\\dev3\www\project"
DirectoryIndex index.php

<Directory "\\dev3\www\project">
    AllowOverride All
    Allow from all
    Options +FollowSymLinks

after restart the apache server, the apache gave me following warning: Warning: DocumentRoot [C:/dev3/www/project] does not exist.

my question is how can i make the apache to recognize my mapped drive