Cortextools not able to get metric names from a Grafana dashboard

[debraj-manna]

I am trying to execute cortextools
to retrieve metric names used in a dashboard file, but it is not generating any output.

debrajmanna@Debrajs-MacBook-Air ~ % cortextool  --log.level=debug analyse dashboard ./tempo-reads-dashboard.json

INFO[0000] log level set to debug

Version

debrajmanna@Debrajs-MacBook-Air ~ % cortextool version
version 0.11.3
checking latest version... You are on the latest version

The dashboard JSON file I have been using is attached.

tempo-reads-dashboard.json