Bulk information send USB

I wish to know that in method to interface printer device to usb we had to
use a Endpoint 0 for control transfers .Wherein in / out information
transfers were by same endpoint 0 .But for bulk transfers a interface uses
Endpoint 8 and 9 . 8 would plain from uc to printer and 9 is incoming for
printer .I am perplexing GET_DEVICE_ID management .. i send it by Ep 8 ..
and i get ack . after that i invalidate ep8 and assent ep 9 to recieve a
twine ...but TRN miscarry doesnt occur .