Hi,
I have used this plugin myself for several projects and am familiar with some of its "quirks". You can see some of my work at trunica.net. There may be some issues with how your application is setup to run in the background and / or with the particular version of the plugin you are using.
For the deliverable of the project do you want a sample app that works using the plugin and demonstrates that the callback is being triggered in the background or do you want it integrated with your app on delivery. If so, would need the source code to your application as well to ensure every works as you intend.
Look forward to helping you out!
Brad Lawrence