The most common problem that we face right after we install amfphp, can be solved by giving write permissions to the php session folder. The amfphp code needs to maintain a session and tries to write some session files in the php session folder. And when it is not able to that because it does not have the required permission, it does not work properly.�

So try giving the required permission to that folder, and it might work for you.

However, there is also another reason for amfphp not working. Sometimes there's an .htaccess file residing in your application folder inside your amfphp folder, which conflicts with the amfphp path. So, removing that file is also one of a solution that you can try. Since mod rewrite and .htaccess doesn't work well with amfphp.