FiFiSDR - complains about snd_pcm_open error

Erwin - PE3ES - F4VTQ

A second Raspberry is running the FiFiSDR

Audio input devices:
**** List of CAPTURE Hardware Devices ****
card 1: FiFiSDR [FiFi-SDR], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: FiFiSDR [FiFi-SDR], device 1: USB Audio [USB Audio #1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
Select audio input device you want to test [0-1] => 1
The audio input to device 1 is being echoed to it line output.  Press ^C (Control+C) to terminate:
sox FAIL formats: can't open output file `hw:1,0': snd_pcm_open error: No such file or directory
Adjust the input gain and restart test? [-+q] =>

This happens when testing either device 0 and 1.

Any suggestions how to get this working would be appreciated.
Thanx, Erwin