The environment in which the application is running which this graph belongs to runs on an old Java 6 32-bit version.
Internal memory management for the 32bit JVM is very different from the 64bit JVM, and I didn' t bother reverse engineering that also when writing the plugin, since we never use the 32bit anywhere any more. The result is that the plugin gets confused and shows an incorrect graph.
If you want to get the graph fixed, I suggest switching to 64bit Java 7, which is a good idea anyway. For this old environment, you have to file a support ticket to get this done.
Did you read the blog post about this feature?
This is a normal picture example.