404 not found issue for first level pages!

Hello Multisite developers,

I installed a WordPress multisite on my localhost under http://localhost/fs/ directory. Therefor my blog URLs will be http://localhost/fs/ for main blog and http://localhost/fs/blog2/ for second blog. Everything works fine except one thing! I see 404 error on frontend for first level pages! For example

http://localhost/fs/sample-page/ Doesn’t work!
http://localhost/fs/sample-page/new-page/ Work
http://localhost/fs/sample-page/new-page/another-page/ Work

Same for second blog.

http://localhost/fs/blog2/sample-page/ Doesn’t work!
http://localhost/fs/blog2/sample-page/new-page/ Work
http://localhost/fs/blog2/sample-page/new-page/another-page/ Work

I’m using the htaccess code that WordPress provide me during Multisite installation:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /fs/
RewriteRule ^index\.php$ - [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).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
</IfModule>

# END WordPress

Please let me know what should I do for fixing this issue!

Regards