Hello,
That message notifies that an update carring the isSnapshot flag set to true was supplied to Lightstreamer Kernel while it was expecting for a non-snapshot event.
To avoid that message you should set the isSnapshot flag (of an update / smartUpdate call) to true only on the first update for an item.
Note that the update is processed normally even if the WARN message is shown.
Take a look to this thread also:
http://www.lightstreamer.com/vb/showthread.php?t=119
Take a look here:
http://www.lightstreamer.com/docs/adapter_java_javadoc/index.html
Hope that helps.