struts 2 中的错误帮忙看看 急！

严重: Exception starting filter struts2
Unable to load bean: type: class:com.opensymphony.xwork2.ObjectFactory - bean - jar:file:/C:/Program%20Files/Apache%20Software%20Foundation/Tomcat%206.0/lib/struts2-core-2.0.8.jar!/struts-default.xml:8:72
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.register(XmlConfigurationProvider.java:208)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.register(StrutsXmlConfigurationProvider.java:101)