我需要帮助确定我的空指针异常来自哪里

I am using PrimeFaces 4.0, NetBeans associated with two xhtml pages. The xhtml renders a select one radio menu from which the user may select an experiment about which they'd like more information. When they do, I'd like for the xhtml to pass the experiment back to java as a string. After the user hits submit, I'd like another xhtml page to open from which the user can further narrow their search criteria. As of right now, when the user clicks submit, there is a null pointer exception. Also, using System.out.println(), I can see that java is not getting the string back from the web page as my Glassfish server output prints (in part) : "Info: nullaaaaaaaaaaaaaaaaaaaaa". It doesn't print the other println() at all.I am using PrimeFaces 4.0, NetBeans associated