很奇怪,jsp在框架页中会出错,而单独使用却正常!

一个jsp页面使用了frameset进行管理三个jsp,结果每个jsp都出现了如下错误,而如果都单独打开却又正常,不知道是怎么回事?
java.lang.NullPointerException
com.sun.faces.el.ValueBindingImpl.<init>(ValueBindingImpl.java:98)
com.sun.faces.application.ApplicationImpl.createValueBinding(ApplicationImpl.java:295)
com.utils.FacesUtils.getValueBinding(FacesUtils.java:182)
com.utils.FacesUtils.getManagedBean(FacesUtils.java:51)
Ajax.treeview.Category.getSQL(Category.java:184)
Ajax.treeview.Category.getChildren(Category.java:119)
org.apache.jsp.Ajax.treeview.dynamicTree_jsp._jspService(org.apache.jsp.Ajax.treeview.dynamicTree_jsp:62)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)