USB Error occured: [Errno 5] Input/Output Error

[chungleepeople]

Hello, I have one product with UT61E+ running in window platform.

When i running these codes, I got [Errno 5] Input/Output Error error message.

message = [0x00, 0x4b, 0x00, 0x00, 0x03]
#dev.ctrl_transfer(bmRequestType, bmRequest, wValue, wIndex, payload)
assert dev.ctrl_transfer(0x21, 9, 0x0300, 0, message) 

I don't have any clue to solve this problem. please help me. thanks