Null Pointer Calling ANT StartBuildTask from Java Code

I am trying to write a Hudson plugin for Jazz SCM. I have followed the basic ANT build tutorials on the Jazz website but need to call the current ANT API from Java if I am to be able to write a usable plugin. I have managed to get the basic plugin skeleton code written for but when I request a build I get the following error:

started



FATAL: java.lang.NullPointerException



java.lang.NullPointerException



	at com.ibm.team.build.ant.task.AbstractTeamBuildTask.execute(AbstractTeamBuildTask.java:432)



	at org.jvnet.hudson.tools.JazzSCM.checkout(JazzSCM.java:130)



	at hudson.model.AbstractProject.checkout(AbstractProject.java:529)



	at hudson.model.AbstractBuild$AbstractRunner.checkout(AbstractBuild.java:223)



	at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:189)



	at hudson.model.Run.run(Run.java:646)



	at hudson.model.Build.run(Build.java:102)



	at hudson.model.ResourceController.execute(ResourceController.java:70)



	at hudson.model.Executor.run(Executor.java:62)



Caused by: java.lang.NullPointerException



	at com.ibm.team.build.ant.task.StartBuildTask.verifyTeamBuildListenerIsActive(StartBuildTask.java:197)



	at com.ibm.team.build.ant.task.StartBuildTask.doExecute(StartBuildTask.java:178)



	at com.ibm.team.build.ant.task.AbstractTeamBuildTask.execute(AbstractTeamBuildTask.java:419)



	... 8 more



--- Nested Exception ---



java.lang.NullPointerException



	at com.ibm.team.build.ant.task.StartBuildTask.verifyTeamBuildListenerIsActive(StartBuildTask.java:197)



	at com.ibm.team.build.ant.task.StartBuildTask.doExecute(StartBuildTask.java:178)



	at com.ibm.team.build.ant.task.AbstractTeamBuildTask.execute(AbstractTeamBuildTask.java:419)



	at org.jvnet.hudson.tools.JazzSCM.checkout(JazzSCM.java:130)



	at hudson.model.AbstractProject.checkout(AbstractProject.java:529)



	at hudson.model.AbstractBuild$AbstractRunner.checkout(AbstractBuild.java:223)



	at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:189)



	at hudson.model.Run.run(Run.java:646)



	at hudson.model.Build.run(Build.java:102)



	at hudson.model.ResourceController.execute(ResourceController.java:70)



	at hudson.model.Executor.run(Executor.java:62)

The code I have which gives this is as follows:

StartBuildTask myStartBuildTask = new StartBuildTask();

String label = (new Date().toString());

myStartBuildTask.setAutoComplete(false);

myStartBuildTask.setBuildDefinitionId(getBuildDefinitionId()); // Prelude Team build 2

myStartBuildTask.setLabel("Build-" + label);

myStartBuildTask.setResultUUIDProperty("buildResultUUID");

myStartBuildTask.setEngineId(getBuildEngineId()); // standalone

myStartBuildTask.setPassword(getPassword()); // build

myStartBuildTask.setRepositoryAddress(getRepositoryLocation()); // https://localhost:9443/jazz

myStartBuildTask.setUserId(getUsername()); // build

        

myStartBuildTask.execute();

My Jazz Server is running and I have my build set up in Jazz as follows:

ID: Prelude Team build 2

Team Area: Prelude Team

Supporting Build Engine: standalone (which is Active (idle), in the Prelude Team Area)

I have tried downloading the source code from Jazz.net, but I cannot find the code for

com.ibm.team.build.ant.task.StartBuildTask.verifyTeamBuildListenerIsActive

I've tried debugging too and looking at the documented API but there seems like there is nothing else I need to provide.

Can anyone point me in the direction of a solution for this problem?

TIA

Cheers, Andrew