Drools called from an EJB do not see objects in working memory

I have and ESB application that calls a custom action. In this custom action I call an EJB session bean. This bean uses Drools to evaluate the incoming object. See the attached application for more information.

When I deploy the application (ant deploy) and run the test (ant runtest) it works well and you can see the following line in the console:
18:07:06,261 INFO [STDOUT] Driver's computed risk group=10

When you redeploy the application (ant undeploy, ant deploy) and run the test again, no rules except for a dummy log rule are evaluated. You can recognize it in the console log:
18:12:34,745 INFO [STDOUT] Driver's computed risk group=0

The rule file is jar/src/org/jboss/soa/esb/samples/quickstart/integration/drools/slsb/RiskGroup.drl. I believe that the issue is with working memory. Simple rule like the following gets evaluated:
rule "log"
dialect "mvel"
when
eval(true)
then
System.out.println("Rules are evaluating");
end

If you configure a rule that grabs any Driver object like the following one, it is not evaluated:
rule "log"
dialect "mvel"
when
p : Driver( )
then
System.out.println("Rules are evaluating");
end

However, the session bean puts a real populated object into it.