Invalid action class configuration that references an unknown class named?

[怪侠]

I use struts2 +spring. My application can work correctly. But if the form 
validation fail, the application can't submit again. Always get the exception: 
Invalid action class configuration that references an unknown class 
named[sysuserAction]. Below is my struts.xml:
   <action name="*SysuserAction" class="sysuserAction"
   method="{1}">
   <interceptor-ref name="token">
    <param name="includeMethods">save,update</param>
   </interceptor-ref>
   <interceptor-ref name="appDefaultStack" />
   <result name="add">/sysuser/addSysuser.jsp</result>
   <result name="list">/sysuser/listSysuser.jsp</result>
   <result name="edit">/sysuser/editSysuser.jsp</result>
   <result name="editInput">/sysuser/editSysuser.jsp</result>
   <result name="invalid.token">/common/invalid.jsp</result>
  </action>
  
 and I define the sysuserAction as a bean in spring.
 Could anyone tell me the reason? 
 Only when validation can't pass, it can't submit again. Even though I fill all 
the form element in correct format.
  
  
 Thanks very much.