FreeMarker template error (HTML_DEBUG mode; use RETHROW in production!)

The following has evaluated to null or missing:
==> tplBase  [in template "WEB-INF/ftl_lib/jeecms/common_tag.ftl" at line 22, column 30]

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Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
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FTL stack trace ("~" means nesting-related):
	- Failed at: ${tplBase}  [in template "WEB-INF/ftl_lib/jeecms/common_tag.ftl" at line 22, column 28]
	- Reached through: #include "${tplBase}/${sysType}/${sol...  [in template "WEB-INF/ftl_lib/jeecms/common_tag.ftl" in macro "Include" at line 22, column 17]
	- Reached through: @cms.Include name="head.html" solutio...  [in template "WEB-INF/user_base/xiaofang_com_www/template/article/xfj/channel.html" at line 12, column 1]
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Java stack trace (for programmers):
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freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:131)
	at freemarker.core.EvalUtil.coerceModelToString(EvalUtil.java:355)
	at freemarker.core.Expression.evalAndCoerceToString(Expression.java:82)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:41)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.MixedContent.accept(MixedContent.java:54)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.Environment.renderElementToString(Environment.java:2196)
	at freemarker.core.StringLiteral.evalAndCoerceToString(StringLiteral.java:96)
	at freemarker.core.Include.accept(Include.java:118)
	at freemarker.core.Environment.visitByHiddingParent(Environment.java:345)
	at freemarker.core.IfBlock.accept(IfBlock.java:48)
	at freemarker.core.Environment.visitByHiddingParent(Environment.java:345)
	at freemarker.core.IfBlock.accept(IfBlock.java:48)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.Macro$Context.runMacro(Macro.java:184)
	at freemarker.core.Environment.invoke(Environment.java:701)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:84)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.MixedContent.accept(MixedContent.java:54)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.Environment.process(Environment.java:302)
	at freemarker.template.Template.process(Template.java:325)
	at org.apache.struts2.views.freemarker.FreemarkerResult.doExecute(FreemarkerResult.java:223)
	at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:191)
	at com.jeecms.core.web.PageCacheResult.execute(PageCacheResult.java:44)
	at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:372)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:276)
	at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
	at com.opensymphony.xwork2.ActionChainResult.execute(ActionChainResult.java:233)
	at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:372)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:276)
	at com.ponyjava.common.struts2.interceptor.UrlInterceptor.doIntercept(UrlInterceptor.java:107)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.jeecms.core.web.CookieIdentityInterceptor.doIntercept(CookieIdentityInterceptor.java:60)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.ponyjava.common.struts2.interceptor.DomainNameInterceptor.doIntercept(DomainNameInterceptor.java:76)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
	at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:575)
	at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)
	at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
	at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
	at com.jeecms.core.web.WebsiteCountFilter.doFilter(WebsiteCountFilter.java:61)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
	at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
	at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3496)
	at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
	at weblogic.security.service.SecurityManager.runAs(Unknown Source)
	at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2180)
	at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2086)
	at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1406)
	at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201)
	at weblogic.work.ExecuteThread.run(ExecuteThread.java:173)