Routing Problem in Multiple Subdomain directory

[eluser]web_developer[/eluser]
Hello,

I have main domain is like www.vehicles.com and have multiple subdomain in that which is like below example.

http://cars.vehicles.com
http://trucks.vehicles.com
http://bikes.vehicles.com
and so on...

http://domain.vehicles.com <-- This is the main domain manager URL.

Directory Flow..

public_html
cars <---- car subdomain directory
index.php
bikes <---- bike subdomain directory
index.php
trucks <---- truck subdomain directory
index.php
domain <---- Main subdomain directory (CI FOLDERS)
system
application
index.php
.htaccess


In all subdomain directory i have change the system & application folder path.
like this.

../domain/system
../domain/application

my default controller in subdomain is vehicle_type

Now when I open http://cars.vehicles.com
then default controller is executing perfectly.. and index action is working fine..

But when I try to open
http://cars.vehicles.com/dealers <-- Dealers action

Then it's not working it's giving me 404 page can not found..

my question is that
index() is working then why dealer() action is not working?


even in routing file i have write the rule
$route[(:any)] = vehicle_type/$1

Still it's not working..

can any body help in this matter? thanks