Another stupid USB mystery

I found that among two of the USB card reader that I have, only the one that takes Memory Stick Pro card (the newer one) works when all my USB Driver related items (USB card reader with external USB harddisk) plug to the USB hub.

Again, I got the result by trial and error :-<.

On the bright side, now I can exchange stuff among all these devices at ease. Gees, I have so many USB related medias.