I am in the process of learning Java and the book I am using has code that requires Java 7. I downloaded the JDK7 developer preview from Google Code so I could add it as a Platform in Netbeans, when I select the 1.7.jdk, file the Next button turns grey for some reason as you can see in the image below:

What am I doing wrong?
Thanks!
Follow these instructions on how to setup Netbean 7 for JDK7.