An error occurred

com.endeca.content.ContentException: For rule [21] : 
	at com.endeca.content.support.ExceptionFactory$MakesContentException.forGeneralError(ExceptionFactory.java:103)
	at com.endeca.content.ene.tags.NavigationRecordsTag.evaluate(NavigationRecordsTag.java:85)
	at com.endeca.content.assembler.TagEvaluator.evaluate(TagEvaluator.java:59)
	at com.endeca.content.assembler.ContentAssembler.evaluate(ContentAssembler.java:82)
	at com.endeca.content.assembler.tags.PropertyTag.evaluate(PropertyTag.java:54)
	at com.endeca.content.assembler.TagEvaluator.evaluate(TagEvaluator.java:59)
	at com.endeca.content.assembler.ContentAssembler.evaluate(ContentAssembler.java:82)
	at com.endeca.content.assembler.tags.ContentItemTag.evaluate(ContentItemTag.java:86)
	at com.endeca.content.assembler.TagEvaluator.evaluate(TagEvaluator.java:59)
	at com.endeca.content.assembler.ContentAssembler.evaluate(ContentAssembler.java:82)
	at com.endeca.content.assembler.tags.ContentItemListTag.evaluate(ContentItemListTag.java:85)
	at com.endeca.content.assembler.TagEvaluator.evaluate(TagEvaluator.java:59)
	at com.endeca.content.assembler.ContentAssembler.evaluate(ContentAssembler.java:82)
	at com.endeca.content.assembler.tags.PropertyTag.evaluate(PropertyTag.java:54)
	at com.endeca.content.assembler.TagEvaluator.evaluate(TagEvaluator.java:59)
	at com.endeca.content.assembler.ContentAssembler.evaluate(ContentAssembler.java:82)
	at com.endeca.content.assembler.tags.ContentItemTag.evaluate(ContentItemTag.java:86)
	at com.endeca.content.assembler.TagEvaluator.evaluate(TagEvaluator.java:59)
	at com.endeca.content.assembler.ContentAssembler.evaluate(ContentAssembler.java:82)
	at com.endeca.content.assembler.ContentAssembler.assemble(ContentAssembler.java:63)
	at com.endeca.content.ene.ENEContentQuery.executeQuery(ENEContentQuery.java:187)
	at com.endeca.content.ene.ENEContentQuery.execute(ENEContentQuery.java:69)
	at com.endeca.content.reference.ContentQueryHandler.submitContentQuery(ContentQueryHandler.java:322)
	at com.endeca.content.reference.ContentQueryHandler.processRequest(ContentQueryHandler.java:178)
	at com.endeca.content.reference.Controller.doGet(Controller.java:156)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:568)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
	at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
	at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:283)
	at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:767)
	at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:697)
	at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:889)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
	at java.lang.Thread.run(Unknown Source)
Caused by: com.endeca.navigation.PartialENEQueryException: Navigation record searches specified with a missing keys or terms or both.
	at com.endeca.navigation.OptiBackend.requestNavigation(Unknown Source)
	at com.endeca.navigation.HttpENEConnection.query(Unknown Source)
	at com.endeca.content.ene.tags.NavigationRecordsTag.evaluate(NavigationRecordsTag.java:82)
	... 41 more