FreeMarker template error!


Expression seo_keyword is undefined on line 7, column 34 in tpl/2014/c/www.china-dental-unit.com/en/inc/title.html.
The problematic instruction:
----------
==> ${seo_keyword} [on line 7, column 32 in tpl/2014/c/www.china-dental-unit.com/en/inc/title.html]
 in include "inc/title.html" [on line 4, column 1 in tpl/2014/c/www.china-dental-unit.com/en/products.html]
----------

Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression seo_keyword is undefined on line 7, column 34 in tpl/2014/c/www.china-dental-unit.com/en/inc/title.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.include(Environment.java:1424)
	at freemarker.core.Include.accept(Include.java:211)
	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:241)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:295)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:235)
	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:102)
	at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
	at shield.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:67)
	at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
	at shield.front.action.filter.InvalidXSSFilter.doFilter(InvalidXSSFilter.java:34)
	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)