Spark Example Plugin not loading

I am trying to learn the basics of creating a plugin for spark. Right now I am simply trying to get the example plugin from the spark dev kit to work, but am running into problems. I am able to compile the plugin using ant and it creates a jar file, but when i copy the jar file to the plugins directory of my spark client (windows) i get the following error in the client log file…

Apr 14, 2008 7:53:40 PM org.jivesoftware.spark.util.log.Log error

SEVERE: Unable to load plugin org.jivesoftware.spark.plugins.myplugin.addButton.

java.lang.ClassNotFoundException: org.jivesoftware.spark.plugins.myplugin.addButton

at$ Source)

at Method)

at Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

at org.jivesoftware.spark.PluginManager.loadPublicPlugin(

at org.jivesoftware.spark.PluginManager.loadPublicPlugins(

at org.jivesoftware.spark.PluginManager.loadPlugins(

at org.jivesoftware.spark.Workspace$

at java.util.concurrent.Executors$ Source)

at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)

at Source)

at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor$ Source)

at Source)

Based on what i have read; i think this has something to do with my plugin.xml file class declaration and the directory structure to my source java file, but am at a loss. Any help would be greatly appreciated.