Xpath query with RMI

Hi,
I would like to execute an xpath query remotly with RMI on my repository.
I have connected to my repository using URLRepository.
I can create my nodes but can't create an XPath query because I can't 
access the workspace :o(
QueryManager manager = session.getWorkspace().getQueryManager(); is 
failing with the following exception :
org.apache.jackrabbit.rmi.client.RemoteRuntimeException: 
java.rmi.ServerException: RemoteException occurred in server thread; 
nested exception is:
    java.rmi.StubNotFoundException: Stub class not found: 
org.apache.jackrabbit.rmi.jackrabbit.ServerJackrabbitWorkspace_Stub; 
nested exception is:
    java.lang.ClassNotFoundException: 
org.apache.jackrabbit.rmi.jackrabbit.ServerJackrabbitWorkspace_Stub
    at 
org.apache.jackrabbit.rmi.client.ClientSession.getWorkspace(ClientSession.java:141)

Is there a workaround to create my xpath query remotely (I am using Jackrabbit 1.4 with core 1.4.5 ?

Thanks,
Emmanuel