Eh cache issues in webMethods 9.0.1

While running a service in webMethods 9.0.1 for which cache is enabled while running with serial processing the results are just fine , when the processing is being concurrent the result is not being pulled from cache and an error is being thrown.

What’s the error?
which Cache is being used?

The error message says: "
2013-10-09 02:53:07 EDT [ISS.0098.0049C] Exception:java.lang.NullPointerException while executing trigger. Rejecting Document for TriggerStore: Packagename:packageFolder.Triggername"

Cache used:We are using on heap cache…

With the same kind of setup cache was working fine for webMethods

As we heard the cache mechanism is changed trying to know what all the changes might be required for us to get everything right.