Alternate Access Mapping On Farm Installation

Hi,

I am having an issue with the alternate access mapping on farm installation. I have a SharePoint farm consist of the following servers

1- Domain Controller Server

2- SharePoint Content Database Server

3- SharePoint Search Database Server

4- Application Server

5- Web front end server

6- Crawling Server

Server 1 and 4 are in the same zones, server 2 and  are in another same zones, server 5 in another zone, server 6 in another zones. And there are firewall among these zones that allow connection on SharePoint needed ports.

My application is working correctly, however I wanted to assign a public IP for the web front end to be accessed from internet. I created a network mapping between the public IP and the server IP. Then I navigated to central administration and configured the Alternate Access Mapping to assign the new mapped IP to the web application on the internet zone.

Now when I try to open the site using the new IP i have a SharePoint  exception "File Not Found" when I navigated to the the logs it found an error "System.IO.FileNotFoundException: The web application at <http://the new IP> could not be found. Verify that ..... etc."

So, I am not sure where the issue is cause it is working from the original IP and not working from the mapped IP

The alternate mapping of the web application is as follows

Internal URLZonePublic URL for Zone

http://<Machine Name>Default http://<Machine Name>

http://<Machine IP>Intranet http://<Machine IP>

http://<Mapped IP>Internet http://<Mapped IP>

I wish to have an answer ASAP please.

Thank you

Ehab