Login again of Reverse proxy configuration into Domino servers

I have 2 servers,“mail.acme.com” is my apache server(I use IBM http Server v7),"host.acme.com"is my Domino Server.in apache server,the following lines are in my Apache httpd.conf configuration file:

LoadModule proxy_module modules/mod_proxy.so

LoadModule proxy_connect_module modules/mod_proxy_connect.so

LoadModule proxy_http_module modules/mod_proxy_http.so

LoadModule rewrite_module modules/mod_rewrite.so

And Apache virtual hosts configuration as follows:

<VirtualHost *>

ServerName host.acme.com

ServerAlias *.host.acme.com

RewriteEngine On

RewriteRule ^/(.*) \http://host.acme.com/$1 [P]

<VirtualHost *>

ServerName mail.acme.com

ServerAlias *.mail.acme.com

RewriteEngine On

ProxyPassReverse / http://host.acme.com/

RewriteRule ^/(.*) \http://mail.acme.com:9001/$1 [P]

I add HTTPEnableConnectorHeaders=1 to notes.ini in Domino Server.

I restart Domino and Apache Server.

Now I use http://mail.acme.com,show iNotes login

page.I input username and password to login,then the url chang to http://host.acme.com/iwaredir.nsf?Open,need me login again.what is the problem?

thanks any comments.

Li wit