the following error while using web logic builder for deploying applciations. Please help
weblogic.management.ApplicationException: Exception:weblogic.management.ApplicationException: Prepare failed. Task Id = 2 Module: myServlets Error: [HTTP:101179][HTTP] Error occurred while parsing descriptor in Web application "C:\bea\myServlets" [Path="C:\bea", URI="myServlets" weblogic.xml.dom.DOMProcessingException: Neither principal-names nor externally-defined element specified for security-role-assignment
at weblogic.servlet.internal.dd.SecurityRoleAssignment.<init>(Lweblogic/serv let/internal/dd/WebAppDescriptor;Lorg/w3c/dom/Element;)V(SecurityRoleAssignment. java:73)
at weblogic.servlet.internal.dd.WLWebAppDescriptor.<init>(Lweblogic/servlet/ internal/dd/WebAppDescriptor;Lorg/w3c/dom/Element;)V(WLWebAppDescriptor.java:147 )
at weblogic.servlet.internal.dd.DescriptorLoader.initializeWebLogic