Make sure you install the software (if you do it from the download) from the account you're trying to use the widget from. As I usually do, I installed the download from my Admin account. Its widget saw the ink levels properly, but my personal account didn't. Downloaded and installed again, from my personal account this time (authenticating when requested) and now it works.
ODD: the widget appears to show correct ink levels, but the tool in HP Utility doesn't. I recently installed both cartridges, and have printed a few pages and a few DVDs. The widget shows both cartridges mostly full, which is "right", while the tool in HP Utility shows a nearly full black cartridge and a nearly empty color cartridge. (Both are genuine HP cartridges.) It's almost as if it's showing %empty instead of %full, though that's conjecture.
Doug