migrating from struts-tiles to tiles 2

[Colyer, Jeffrey]

Hi,
I'm trying to do the migration and keep my existing tiles-defs.xml files.  
Right now I've pulled the tiles 2.1.1 jars.  I've tried several different 
configurations in my web.xml to make this work, but haven't had any luck.  I'm 
using some init-param's to override some of the methods with the 
tiles-compat.jar.   I currently get the following error:
java.lang.NullPointerException
        
org.apache.tiles.web.util.TilesDispatchServlet.doGet(TilesDispatchServlet.java:87)

Does anyone know if there's a setup issue or if something else I should try.  
Here's a snippet from my web.xml:
    <servlet>
        <servlet-name>TilesDispatcher</servlet-name>
        
<servlet-class>org.apache.tiles.web.util.TilesDispatchServlet</servlet-class>
        <init-param>
            
<param-name>org.apache.tiles.definition.DefinitionsFactory.DEFINITIONS_CONFIG</param-name>
            
<param-value>/WEB-INF/tiles-defs.xml,/WEB-INF/tiles-defs-tc.xml</param-value>
        </init-param>
                                <init-param>
                                                
<param-name>org.apache.tiles.definition.DefinitionsReader</param-name>
                                                
<param-value>org.apache.tiles.compat.definition.digester.CompatibilityDigesterDefinitionsReader</param-value>
                                </init-param>
                                <init-param>
                                                 
<param-name>org.apache.tiles.renderer.impl.BasicRendererFactory.TYPE_RENDERERS</param-name>
                                     <param-value>
                                                                 
string,org.apache.tiles.renderer.impl.StringAttributeRenderer;
                                                                 
definition,org.apache.tiles.renderer.impl.DefinitionAttributeRenderer;
                                                                 
template,org.apache.tiles.renderer.impl.TemplateAttributeRenderer;
                                                                 
page,org.apache.tiles.renderer.impl.TemplateAttributeRenderer
                                                 </param-value>
                                 </init-param>
    </servlet>

    <servlet-mapping>
                                <servlet-name>TilesDispatcher</servlet-name>
                                <url-pattern>*.tiles</url-pattern>
    </servlet-mapping>

Thanks,
Jeff

________________________________
This e-mail message, including any attachments, is for the sole use of the 
intended recipient(s) and may contain information that is confidential and 
protected by law from unauthorized disclosure. Any unauthorized review, use, 
disclosure or distribution is prohibited. If you are not the intended 
recipient, please contact the sender by reply e-mail and destroy all copies of 
the original message.