XML related libraries are already included in the latest JDKs.
Anyway, problems from missing libraries should manifest themselves
in a clear way.

There may be a mismatch in the item or field names used.
Note that both item and field names have to be asked for by client code.
A problem of this kind could be put into evidence through the Server log,
by setting the priority of the "LightstreamerLogger.subscriptions" and "LightstreamerLogger.pump" categories to DEBUG in "lightstreamer_log_conf.xml".