Access_to_Resource_IS_Forbidden Error when Undeploying vApp with Java API

I want to undeploy a vApp using the Java APIs.  The vApp was created in a different program using the Java APIs.  The same user ID is used to log in in both programs.  However, when I try to execute undeploy(UndeployPowerActionType.Force).waitForTask(0), I get the Access_to_Resource_is_forbidden_error.  I modeled my program after the HellovCloud sample program.  Here is the flow:

vcloudClient.login();

org = Organization.getOrganizationByReference()

vdcRef = org.getVdcRefByName()

vdc = Vdc.getVdcByReference()

vappRefs = vdc.getVappRefs()

vapp = Vapp.getVappByReference()

vapp.undeploy(UndeployPowerActionType.FORCE).waitForTask(0).  // ACCESS_TO_RESOURCE_IS_FORBIDDEN

I am able to execute "vapp.powerOff().waifForTask(0)" before the undeploy.  However I get the undeploy error whether I first powerOff the vapp or not.

Any ideas on why this is occurring and how to overcome it?  I'm using vCloud Director 5.1.  Thanks very much.