I had a similar problem on my roadster from the factory. Changed tubes, still didn't work. I didn't have another tank to try, but the shop I bought it from took it back and sold me their other one and sent the first one off to be fixed. When it came back they told me a component had failed. Not sure which part, but An authorized tech would be able to fix it I think. FWIW, my first roadster was purchased around May of 09, not sure of manufacture date, while the second one is from mid summer and manufactured no earlier than May or June I suspect. The difference in serial numbers was about 200.
Sorry I don't have any more to contribute. Maybe if you posted a picture of the component in question, the more knowledgable forum members could identify the mystery component.