Problem with loading an XML file or writing to it

I have a GUI application which reads data from an XML file (current_users.xml) and also writes to that XML file. GUI is placed at /var/www/bin-release and XML files are located in the directory /home/os/work2/project/

The GUI expects the XML file to be in the directory: /var/www/bin-release. So I created a symlink to /home/os/work2/project/current_users.xml in /var/www/bin-release. This with some other settings given below works fine on a number of PCs but on one particular PC, this setup does not cause the GUI to access the XML file rightly i.e. it neither reads nor writes to the XML file.

sudo ln -s /home/os/work2/current_users.xml /var/www/bin-release/current_users.xml
sudo chmod ug+rwx -R /var/www/bin-release
sudo chown $USER:www-data -R /var/www
sudo chown root:root /home/os/work2/current_user.xml
sudo chmod 666 /home/os/work2/current_users.xml
sudo usermod -a -G www-data $USER

Apache is being run by www-data as viewed via the output of ps -aux | grep apache

Warning: bad ps syntax, perhaps a bogus '-'? See http://procps.sf.net/faq.html
root      1442  0.0  0.3  36372  7528 ?        Ss   11:22   0:00 /usr/sbin/apache2 -k start
www-data  1452  0.0  0.3  36972  6308 ?        S    11:22   0:00 /usr/sbin/apache2 -k start
www-data  1453  0.0  0.3  36948  6300 ?        S    11:22   0:00 /usr/sbin/apache2 -k start
ww开发者_如何学编程w-data  1454  0.0  0.3  36836  6292 ?        S    11:22   0:00 /usr/sbin/apache2 -k start
www-data  1455  0.0  0.2  36948  4820 ?        S    11:22   0:00 /usr/sbin/apache2 -k start
www-data  1457  0.0  0.2  36948  4724 ?        S    11:22   0:00 /usr/sbin/apache2 -k start
www-data  2325  0.0  0.2  36700  4656 ?        S    11:24   0:00 /usr/sbin/apache2 -k start
www-data  2343  0.0  0.2  36700  4656 ?        S    11:24   0:00 /usr/sbin/apache2 -k start
www-data  2344  0.0  0.2  36460  4864 ?        S    11:24   0:00 /usr/sbin/apache2 -k start
tahir     6686  0.0  0.0   4012   764 pts/0    S+   11:50   0:00 grep --color=auto apache

You might not have permission to enter the directory:

$ chmod +x /home/os/work2/