HackRF One as transciever with GRC

[ianyappy]

I've been trying to set up the HackRF One operating as a transceiver (or at least switching dynamically between Tx/Rx at runtime) and have used this (http://w7fu.com/?page_id=190) as a base example. My simplified code is as shown in the picture. The error message that I get is:

"FATAL: No supported devices found to pick from.

Trying to fill up 1 missing channel(s) with null sink(s).

This is being done to prevent the application from crashing

due to gnuradio bug #528."

Program can run (default at Rx) but crashes when I switch to Tx. Would appreciate any assistance on this. Is this even possible with GRC?