Hmm, that is an interesting one.
If your app works fine in development and when deployed to a test device, then there should be no reason why it should work when it is published, unless there is no network connectivity on the device.
I would check that the configuration xml file you are using is set to "copy" to the output folder and / or that your remote XML file is accessible from the device (you should be able to browse to it).
If you are still having trouble, try creating a sample project using your config and put it on drop box and we'll check it out.
This is the V1 codeplex site. for V2 you should log your issues on the V2 site here: