Cannot access subpage url of subdomain - php

Question

I did a rewrite rule for wildcard subdomain access to allow me to access any countries of my list page as follows:
RewriteCond %{HTTP_HOST} ^(.+)\.mydomain\.net$
RewriteCond %{HTTP_HOST} !^www\.mydomain\.net$
RewriteCond %{REQUEST_URI} !^.*\.(jpe?g|png|gif|bmp)$ [NC]
RewriteRule (.*) pages/list.php?country=%1 [L]
This is working fine.
Now. I do a rewrite rule to access another page on the domain but i keep getting referred back to the list page.
RewriteRule ^ad/([A-Za-z0-9-]+)?$ pages/details.php?alias=$1 [NC,L]
My end result is to access eg: http://us.mydomain.net/ad/alias but it keeps referring me back to the list page.
UPDATED REWRITE RULES(AS OF 14 MAY)
RewriteEngine on
<IfModule mod_headers.c>
Header set Access-Control-Allow-Origin "*"
</IfModule>
RewriteRule ^cat/([A-Za-z0-9-]+)/?$ ?category=$1 [L,QSA,NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{HTTP_HOST} ^(.+)\.ibizportal\.net$
RewriteCond %{HTTP_HOST} !^www\.ibizportal\.net$
RewriteCond %{REQUEST_URI} !^.*\.(jpe?g|png|gif|bmp)$ [NC]
RewriteRule (.*) pages/list.php?country=%1 [L]

Answer 1

Change first rule to:
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^cat/([A-Za-z0-9-]+)/?$ ?category=$1 [L,QSA,NC]
RewriteCond %{HTTP_HOST} ^((?!www).+)\.mydomain\.net$ [NC]
RewriteCond %{REQUEST_URI} !\.(?:jpe?g|png|gif|bmp|php)$ [NC]
RewriteRule (.+) pages/list.php?country=%1 [L,QSA]