Trouble in extending packages in Struts2.xml

My struts.xml is configured as

<package name="Base" extends="struts-default">
<interceptors>
<interceptor name="xssFilterInterceptor"
class="XSSFilterInterceptor">
</interceptor>

<interceptor-stack name="criteriaInterceptorStack">
<interceptor-ref name="defaultStack" />
<interceptor-ref name="xssFilterInterceptor" />
</interceptor-stack>

</interceptors>

<default-interceptor-ref name="criteriaInterceptorStack" />
<global-results>

<result name="errorPage">/common/servletErrPage.jsp</result>
</global-results>

</package>

<package name="com.mastercard.mastercom.casefilling.web.action"
extends="Base">

action configuration here
</package>

on trying to run the application i am getting some error as
[Servlet Error]-[Filter [struts2]: could not be initialized]: Unable to load configuration. - package - file:/E:/pjt-web/WebContent/WEB-INF/classes/struts.xml: (line number which states extends = "Base")

Any idea, i searched info, yet no solution

Please UseCodeTags when posting code or configuration. Unformatted code and configuration is unnecessarily difficult to read. You can edit your post by using the

button.

Stacktrace from log with devMode turned on and logging at DEBUG level?

I'd also be wary of naming a package with a full-on Java qualified package name; it can confuse things, particularly when using some of the plugins. I think. I don't recall now.