子目录中的自定义链接('/')重定向到主目录

I change my wordpress installation to my subdirectory. But my custom link / in one menu item redirect to home directory.

Such as my parent domain is maindomain.com and my wordpress installation is in maindomain.com/wordpress/site1

Now when I click on the site1 menu item which contain custom link / then it take me to the maindomain.com not in the maindomain.com/wordpress/site1 .

I want it to take me maindomain.com/wordpres/site1

My .htaccess rule for site1 is below

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /wordpress/valley/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /wordpress/valley/index.php [L]
</IfModule>

Note: I have no files in the maindomain.com