BuddyPress.org

PROBLEM SOLVED!
The problem is “404 Redirection” plugin. Disabling this plugin now Buddypress work fine.

It not resolve my problem. My .htaccess now is

RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ – [L]

deny from all

order deny,allow

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ – [L]
RewriteRule ^[_0-9a-zA-Z-]+/(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^[_0-9a-zA-Z-]+/(.*.php)$ $1 [L]
RewriteRule . index.php [L]