I used the EHSETT tool to test the usb2.0 device（cyusb2014）compliance , When I teste the Device Receiver Sensitivity ,I could not get the correct result.
First I setted the device to SE0_NAK mode, And than used the Signal generator to send IN pakcet to the device,
But The USB2.0 Device can not return the NAK packet .
I am sure that the device connections and corresponding steps are correct ，because other usb2.0 device was correct .
Why the device could not return the NAK when received the IN packet in SE0_NAK mode ?