Tomcat 5.0 with Restlet 1.1 throws nullpointer exception

[Surjendu]

When I use Tomcat 5.0 with the following restlet jars(1.0.9) 
my application works fine.

org.restlet.jar(175,240)
com.noelios.restlet.jar(150,630)
com.noelios.restlet.ext.servlet_2.4.jar(14,115)

When I try to use Tomcat 5.0 with the following 
restlet jars (1.1) my applications conks off.

org.restlet.jar(193,268)
com.noelios.restlet.jar(164,645)
com.noelios.restlet.ext.servlet_2.4.jar(14,795)

I get the following exception

java.lang.NullPointerException
        at java.util.concurrent.CopyOnWriteArrayList.
<init>(CopyOnWriteArrayList.java:69)
at org.restlet.Connector.<init>(Connector.java:69)
at org.restlet.Client.<init>(Client.java:49)
at com.noelios.restlet.ext.servlet.ServletWarClient.
<init>(ServletWarClient.java:52)
at
com.noelios.restlet.ext.servlet.ServerServlet.
createApplication(ServerServlet.java:215)
at
com.noelios.restlet.ext.servlet.ServerServlet.
getApplication(ServerServlet.java:313)
at com.noelios.restlet.ext.servlet.ServerServlet.
init(ServerServlet.java:418)

why is this happening??