RA2A1 write operation return FSP_ERR_USB_BUSY in PHID mode

HI, 

Recently i am using the PHID mode of USB, it can enumerate successfuly, but when i try  using the write operation to send key buffer to computer, it return an error of  FSP_ERR_USB_BUSY, and it never be free,how can i get out of this statues? I have try to close the use and open again, it still return the same error.

p.s.  the demo project can work well now, and i make another project that use non-os, it still work well. But when i add those code into my product's project, it get error.

Hope someone can help me, thanks.