将文件上载到Apache别名目录和子目录

I have two virtual hosts on my server. One "web" and one "mobile". I can view files from the "web" under the directory "users" normally but I cannot upload or create directories under it?!!

for example:

<img src='http://m.domain.com/users/imgs/sample.png' /> this is viewable 

//this is not possible
<?php 
  mkdir("users/newDir"); //fails

  $img = file_get_contents("http://images.devshed.com/fds/belts/ds_forums.gif");
  $file = "users/newDir/sample.gif";
  file_put_contents($file, $img); //fails

  $img = file_get_contents("http://images.devshed.com/fds/belts/ds_forums.gif");
  $file = "users/sample.gif";
  file_put_contents($file, $img); //fails

?> 

I have the following under my mobile virtual to point to the files on my "web":

<VirtualHost *:80>
ServerName domain.com
ServerAlias m.domain.com

 DocumentRoot "C:/Apache/mobileroot"
 <Directory "C:/Apache/mobileroot">
     Options FollowSymLinks
     AllowOverride None
     Order allow,deny
     Allow from all
 </Directory>

 Alias /users/ "C:/Apache/webroot/users/"
 <Directory "C:/Apache/webroot/users/">
    Options Indexes MultiViews
    AllowOverride None
    Order allow,deny
    Allow from all
 </Directory>
</VirtualHost>

To answer my own question if someone stumbled the same issue in the future.

Under the mobile directory all references to write had to switch them to absolute path the case of mkdir("users/newDir");

So on the "web" directory it stays the same but on the "mobile" directory I changed all write actions to use absolute path like:

mkdir("C:/Apache/webroot/users/newDir");

This forces the new directory "newDir" to be created on the "web" not on the "mobile" directory on the server.