apache httpd serveralias only one domain not working - apache

Question

I have a server for 10 domains. all domains are working fine with ServerAlias so if user type www.domain.com or just domain.com works perfect. However, only one domain does not work. If I type www.xxxxx.com, it works. If I type just xxxxx.com, it goes to default page. Since other domains does not have this problem, How can I fix it? or how can I check ServerAlias result in httpd?
<VirtualHost 202.64.x.x:80>
ServerName www.xxxxx.com:80
ServerAdmin webmaster#xxxxx.com
DocumentRoot /var/www/web185/web
ServerAlias xxxx.com.hk
DirectoryIndex index.html index.htm index.php index.php5 index.php4 index.php3 index.shtml index.cgi index.pl index.jsp Default.htm default.htm
Alias /cgi-bin/ /var/www/web185/cgi-bin/
AddHandler cgi-script .cgi
AddHandler cgi-script .pl
ErrorLog /var/www/web185/log/error.log
AddType application/x-httpd-php .php .php3 .php4 .php5
php_admin_flag safe_mode On
php_admin_value open_basedir /var/www/web185/
php_admin_value file_uploads 1
php_admin_value upload_tmp_dir /var/www/web185/phptmp/
php_admin_value session.save_path /var/www/web185/phptmp/
AddType text/html .shtml
AddOutputFilter INCLUDES .shtml
AddType application/vnd.wap.wmlscriptc .wmlsc .wsc
AddType text/vnd.wap.wml .wml
AddType text/vnd.wap.wmlscript .ws .wmlscript
AddType image/vnd.wap.wbmp .wbmp
Alias /stats "/var/www/web185/web/webalizer"
Alias /error/ "/var/www/web185/web/error/"
AliasMatch ^/~([^/]+)(/(.*))? /var/www/web185/user/$1/web/$3
AliasMatch ^/users/([^/]+)(/(.*))? /var/www/web185/user/$1/web/$3
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{REQUEST_METHOD} ^(TRACE|TRACK)
RewriteRule .* - [F]
</IfModule>
</VirtualHost>

Answer 1

ServerAlias xxxx.com.hk
This means that the alias is xxxx.com.hk and not xxxx.com and hence xxxx.com goes to the default page.