[S2] Getting error while running struts project

[Anjib Mulepati]

Hi I am trying to run the Struts2 project in Netbeans . I have included 
all necessary jar files. But i am getting following error:

SEVERE: Exception starting filter struts2
java.lang.NoSuchMethodError: 
com.opensymphony.xwork2.util.finder.ClassFinder.

What does this mean? And how can i fix this?

Thanks,
Anjib