PW running on other Domain/Server than the Domain, using .htaccess

[Frangoo]

Hi,
 
I am sorry to aks that, as I am not sure if I am just blind :-|
 
My situation: I created PW on server A, having Domain A. Everthing fine, but my customer wants to keep his Domain on his server
To keep hes Domain present in the url-box of the browser, I use a forward with htaccess on his Server.
 
My htaccess looks like that:
 
Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /

RewriteCond %{HTTP_HOST} ^(www\.)?domain-a\.com$ [NC]
RewriteRule ^ http://pw.domain-b.com/%{REQUEST_URI} [L,NE,P]
 
 
But PW is not able to retrieve the correct page, because I am always seeing the 404-error-template.
 
Does anyone has an Idea, where I can have a look to find the error? I guess any server-parameter is wrong and I have to adjust it.
Calling PW directly with the url on domain-b works.

Thanks a lot for any hint!

[DaveP]

Can he not point his name server at your server? A domain doesn't really live on a server or anywhere else, for that matter. A domain is essentially just a human-friendly name for an IP address.

[BitPoet]

Is mod_proxy active on server a?

Edit: with server a I mean the customer's original server.

[Frangoo]

Thanks for your comments!!!

I do not think he has any idea what nameserver means and how to change. But prop will be the only valid way to do that. I will talk with the customer.

And also I do not know if mod_proxy active.

I will find out, thank you !