FreeMarker template error!


Expression introID is undefined on line 9, column 51 in tpl/2015/c/www.cleanoil.com.hk/zh-TW/career_detailed.html.
The problematic instruction:
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==> ${introID} [on line 9, column 49 in tpl/2015/c/www.cleanoil.com.hk/zh-TW/career_detailed.html]
 in user-directive mytag.viewIntroduce [on line 9, column 1 in tpl/2015/c/www.cleanoil.com.hk/zh-TW/career_detailed.html]
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Java backtrace for programmers:
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freemarker.core.InvalidReferenceException: Expression introID is undefined on line 9, column 51 in tpl/2015/c/www.cleanoil.com.hk/zh-TW/career_detailed.html.
	at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:124)
	at freemarker.core.Expression.getStringValue(Expression.java:118)
	at freemarker.core.Expression.getStringValue(Expression.java:93)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
	at freemarker.core.Environment.visit(Environment.java:245)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:245)
	at freemarker.core.Environment.renderElementToString(Environment.java:1510)
	at freemarker.core.StringLiteral.getStringValue(StringLiteral.java:95)
	at freemarker.core.StringLiteral._getAsTemplateModel(StringLiteral.java:80)
	at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:110)
	at freemarker.core.Environment.visit(Environment.java:245)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:245)
	at freemarker.core.Environment.process(Environment.java:225)
	at freemarker.template.Template.process(Template.java:117)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:310)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:245)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:114)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:91)
	at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:103)
	at shield.front.action.filter.NotAllowedToTunFilesFilter.doFilter(NotAllowedToTunFilesFilter.java:127)
	at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
	at shield.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:81)
	at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
	at shield.front.action.filter.InvalidXSSFilter.doFilter(InvalidXSSFilter.java:93)
	at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
	at com.caucho.filters.GzipFilter.doFilter(GzipFilter.java:151)
	at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
	at com.caucho.server.cache.CacheFilterChain.doFilter(CacheFilterChain.java:192)
	at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:187)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:265)
	at com.caucho.server.hmux.HmuxRequest.handleRequest(HmuxRequest.java:436)
	at com.caucho.server.port.TcpConnection.run(TcpConnection.java:682)
	at com.caucho.util.ThreadPool$Item.runTasks(ThreadPool.java:743)
	at com.caucho.util.ThreadPool$Item.run(ThreadPool.java:662)
	at java.lang.Thread.run(Thread.java:662)