Sharing Document Root, PHP Not Executing

[dndco]

I have one domain running WordPress. It works.

I created a second domain and made its document root the same as domain1 following;
http://onlinehowto.net/Tutorials/Pl...ocumentRoot-folder-in-Apache-with-Plesk/175/2

When you visite domain2 in a browser the page is white. By viewing the source you can see the raw PHP code of the WordPress index.php has not been executed.

How can I resolve this?

Thanks!