Cannot access the web server. The server may not be running or the web root folder or root URL may

I have installed the Flash Builder and Zend Server. While generating a new mobile project in php, I am a getting the following error when I try to validate configuration:

Cannot access the web server. The server may not be running or the web root folder or root URL may be or root URL may be invalid.

I don't understand. I did everything such as making the folders as share folders, giving them permissions, e.t.c.

Here are my settings:

Web root: /usr/local/zend/apache2/htdocs

Root URL: http://localhost:10081/

Output Folder: /Users/fatihsen/Desktop/PhpMobileProject

I would be very glad if someone could help me with that.