Follow others custom usb hid demo but not work.

I first used a stm32f103 board,after generated code and configurated usbd_custom_hid_if.c and then download the code,my computer cant recognize the usb device.Then I changed to a f407 board, after done the same work,my computer can recognize the device as a hid device.But unfortunately the funcation "USBD_CUSTOM_HID_SendReport(&hUsbDeviceFS,sendbuffer,2)" seems not work,my computer cant receive any data from the board.