Struts 2 validation not working - validation

Question

I am trying to use struts 2 custom validation framework for validations, however that does not seem to be working. I am working on a very big project and the module I'm working on, I'm trying to implement this.
The problem struts 2 is not detecting my validation.xml. I tried creating a sample project and and used this validation.xml and it is working, but the same is not working in the project.
I am using model driven , I hope that should not be the problem.
The basic validations provided by action support are working fine but not my validations.
<interceptors>
<interceptor name="multiselect" class="org.apache.struts2.interceptor.MultiselectInterceptor" />
<interceptor name="browserCachingInterceptor" class="com.comviva.im.ui.interceptor.BrowserCachingInterceptor" />
<interceptor name="sessionHijackInterceptor" class="com.comviva.im.ui.interceptor.SessionHijackInterceptor" />
<interceptor name="tokenSession" class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor" />
<interceptor-stack name="defaultSecurityStack">
<interceptor-ref name="defaultStack">
<param name="exception.logEnabled">true</param>
<param name="exception.logLevel">DEBUG</param>
</interceptor-ref>
<interceptor-ref name="tokenSession">
<param name="excludeMethods">*</param>
</interceptor-ref>
<interceptor-ref name="sessionHijackInterceptor" />
<interceptor-ref name="browserCachingInterceptor" />
</interceptor-stack>
</interceptors>
<default-interceptor-ref name="defaultSecurityStack"></default-interceptor-ref>
The interceptor declaration is also fine.
I tried for days but still cant figure out the problem. the only option remaining is debug.
Can anybody suggest me where should I be looking for. Where is the validation.xml file is loaded in ActionInvocation so that I can check if validation file was loaded properly or not.
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE validators PUBLIC "-//Apache Struts//XWork Validator 1.0.3//EN"
"http://struts.apache.org/dtds/xwork-validator-1.0.3.dtd">
<validators>
<field name="nodeId">
<field-validator type="required">
<message key="errors.required"/>
</field-validator>
<field-validator type="int">
<param name="min">1</param>
<param name="max">10000</param>
<message>bar must be between ${min} and ${max}, current value is ${bar}.</message>
</field-validator>
</field>
<field name="selfISDNNumber">
<field-validator type="required">
<message key="errors.required"/>
</field-validator>
</field>
</validators>
This is extract from my action class:
public class NodeAction extends BaseAction implements ModelDriven<NodeConfigurationForm>, ParameterAware ,Preparable {
NodeConfigurationForm nodeConfigForm = new NodeConfigurationForm();
private static final Logger logger = Logger.getLogger(NodeAction.class);
private NodeConfigurationService configurationService;
private List<NodeConfiguration> nodeListTable = null;
Map<String , String[]> requestParams;
private int isFallBackChannelEnable;
private int smsSupportEnable;
private ServletContext servletContext;
MY NodeAction class extends BaseAction which extends ActionSupport which by default is validation aware.So NodeAction should work with custom validations also.
This is extract from my struts.xml regarding actions:
<action name="createGWNode" method="create" class="com.comviva.im.ui.ussdGateway.action.NodeAction">
<result name="success" type="tiles">createGWNode</result>
</action>
<action name="addGWNode" method="add" class="com.comviva.im.ui.ussdGateway.action.NodeAction">
<result name="success" type="chain">listGWNodes</result>
<result name="input" type="tiles">createGWNode</result>
<result name="error" type="tiles">createGWNode</result>
</action>
<action name="editGWNode" method="edit" class="com.comviva.im.ui.ussdGateway.action.NodeAction">
<result name="success" type="tiles">createGWNode</result>
</action>
<action name="updateGWNode" method="update" class="com.comviva.im.ui.ussdGateway.action.NodeAction">
<result name="success" type="redirect">listGWNodes</result>
<result name="input" type="tiles">createGWNode</result>
<result name="error" type="tiles">createGWNode</result>
</action>
And this is my jsp
<s:textfield name="nodeId" required="true" theme="simple" />reado
<s:radio name="status" list="#{'1':'Enable','0':'Disable'}" theme="simple"></s:radio>
<s:textfield name="gwInstanceName" theme="simple" />
<s:textarea name="description" cols="30" rows="2" theme="simple"/>
<s:textfield name="serverIp" theme="simple"/>
<s:textfield name="serverIp" theme="simple" readonly=< s:textfield name="loginUserId" theme="simple"/>
<s:password name="loginPassword" showPassword="true" theme="simple"/>
<s:textfield name=" selfISDNNumber " theme="simple "/>
<s:select name="logLevel " list="logLevelList " theme="simple "/>

Answer 1

Note: Please remove _ Underscore from selfISDN_num
Check proper jar files.
Xwork: Core 2.3.16.2 API
And check getter , setters
Note: Please check package name in struts.xml, does it extend struts-default?
<package name="Registration" namespace="/" extends="struts-default">
...
</package>

Answer 2

Finally found what was going wrong.
The DTD specified in validaiton.xml was wrong. The specifed DTD is for 2.3 onwards. I was using struts with a lower version.
I am now using
<!DOCTYPE validators PUBLIC
"-//OpenSymphony Group//XWork Validator 1.0//EN"
"http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">