HI,
when I run your process (but with my simple test classes - you did not attach source) including your configuration test fails indeed.
What I did to make it to work was to disable jobexecutor in jbpm.cfg.xml. After that change test went well. I tested that for both 4.3 and 4.4.
If that would not help you please post source for custom nodes I will try to dig a bit deeper.
HTH
Maciej