IOCTL代码中BULK传输为什么不能运行？但控制传输可以，代码如下：

if (bOpenDriver(&hDevice,m_strDeviceName))
{
// build VENDOR_OR_CLASS_REQUEST_CONTROL structure
   vendreq.direction = 0; // host to device
vendreq.requestType = 2; // vendor request
vendreq.recepient = 0; // recipient is device
vendreq.requestTypeReservedBits = 0; // not used
vendreq.request = 0xB8; // request value = 0xB2
vendreq.value = 0; // not used
vendreq.index = 0; // not used

  // write to HPIA register
bResult = DeviceIoControl(hDevice, // device handle
 IOCTL_EZUSB_VENDOR_OR_CLASS_REQUEST, // dwIoControlCode
     &vendreq,        // ptr to vend req struct
     sizeof(VENDOR_OR_CLASS_REQUEST_CONTROL), // input buffer size
     &Read_addr, // data to send
     sizeof(Read_addr), // size of output buffer
     &nBytes, // required dummy var
     NULL);    

     btc.pipeNum = 6; // EP6In is pipe 6
bResult = DeviceIoControl (hDevice,
IOCTL_EZUSB_BULK_READ,
&btc,
sizeof (BULK_TRANSFER_CONTROL),
In_Buffer,
Read_length,
(unsigned long *)&nBytes,
NULL);

难道做BULK传输还需要一些其他动作？

多谢，早已搞好。程序下载，BULK传输都可以，但有时需要传两次，怎么才能复位端点？