hidapi libusb_claim_intetface return LIBUSB_ERROR_BUSY,but hid is not active

[Huimieer]

the follow code snippet come from libusb/hid.c.
`res = libusb_open(usb_dev, &dev->device_handle);

/* Detach the kernel driver, but only if the device is managed by the kernel */
if (libusb_kernel_driver_active(dev->device_handle, intf_desc->bInterfaceNumber) == 1) {

res = libusb_detach_kernel_driver(dev->device_handle, intf_desc->bInterfaceNumber);

res = libusb_claim_interface(dev->device_handle, intf_desc->bInterfaceNumber);
if (res < 0) {...... }`

Description:
the problem is that libusb_claim_interface always return -6 after the libusb_open() has been excuted successfully.
but libusb_kernel_driver_active(dev->device_handle, intf_desc->bInterfaceNumber) don't equal to 1, so it won't do the detach operation. Why?