UMR2 pass thru not working

I have no MIDI output messages. Just stucked with it. Please help!

  1. usb2midi adapter generates MIDI messages. I checked this with logic analyzer with appropriate protocol sniffer, by connecting it to OUT port on adapter using wires DIN 5 (-) and GND
  2. UMR2 receives messages, flashing the red LED on each message
  3. no output is generated on UMR2 midi OUT port: DIN 4 (+) and GND - 5v present, but no signals; DIN 5 (-) and GND - 5v present, but no signals. usb2midi adapter doesn’t catch signals either.