USBDev_CDCDataReceived

[kpayea]

Hello All:
I have a PIC24EP512GU810 processor, using MikroC Pro under Windows 10. I have installed the USB CDC Device driver from Libstock. I believe it is the latest version.
Transmitting data to a host is working fine. I put out a CSV string of telemetry data every 10 seconds. It shows up in TeraTerm as it should.

I'm having a problem receiving data from the host. I built the application based on the CDC example code that came with the library.
I am setting up the buffer with USBDev_CDCSetReceiveBuffer as shown in the example.
When I send characters from TeraTerm to the device, USBDev_CDCDataReceived is never called, and the buffer never has characters in it.
I've tried sending long strings and lots of newlines.

Can you give me some idea where to look for the problem?

Thanks, Keith