set up USB keyboard and mouse?

i used platform builder 4.2  to create image file and transfer to my 
device(set top box). at command line(dos interface), i can use usb 
keyboard. but when i start up with window interface(run nk.bin), usb 
keyboard and mouse is not available to use. 
Anyone can help me to config this problem? 
How to config a right driver for usb keyboard in platform builder?

The platform i used is just a evaluation version. 





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