Why is horde or webmail showing blank page ?

Issue : Horde is showing blank page while someone is accessing the webmail interface.
Solution :

I got this issue when one customer had notified it. It usually happens if path of the horde libray is not defined in the /etc/httpd/conf.d/zz010_psa_httpd.conf file. So,
a)edit the /etc/httpd/conf.d/zz010_psa_httpd.conf file
b) Find the directive "Include".
Example :

Before :
---------------
php_admin_value
include_path "/usr/share/psa-horde:/usr/share/psa-horde/pear:."
---------------

After (Correct) :

----------
php_admin_value
include_path "/usr/share/psa-horde/lib:/usr/share/psa-horde:/usr/share/psa-horde/pear:."
----------

c)Then restart the httpd service. That's it.