wp_get_current_user() function returns 0 always

Hi,

i have recently upgrade the wordpress to multisite in my clients site..

for your reference here is the link…
realestate.nyasatimes.com

even after i logged as admin, current user always shows as 0.. i dont know where the issue was.. was googling for last 6 hours and tried some thing nothing helped me 🙁

so finally i am here to seek your help.. your time to read my question is much appreciated. pls help me to cross this issue..

here is .htaccess file for your reference

RewriteEngine On
#redirect to www for the main site
RewriteCond %{HTTP_HOST} ^nyasatimes\.com
RewriteRule ^ http://www.nyasatimes.com/%{REQUEST_URI} [L,R=301]

RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule . index.php [L]