microKey + USB hub + 3rd party CCK = 'not supported'?

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Anyone experience "This accessory is not supported on the iPad" pop-up message when using USB devices with a CCK?

I'm using a Korg microKey via a powered USB hub with a third party Camera Connection Kit on my iPad and I always get this pop-up within a few minutes of use. Clicking OK lets me continue working as before, as long as I'm using the powered hub, but would be interested to know that replacing the third party CCK with a genuine Apple one would eliminate the annoying pop-up message.