Are you measuring the humidity for your cigars? 
This just became much more interesting. What tech are you using?
Back to the issue…
If you arer run the query on Prometheus. is everything working as expected? ( http://localhost:9090/graph ) what kind of numbers can you see?
Would also be great if you could include the response from prometheus from your query in the panel. We have a guide for how to do that here How To Use Grafana's Query Inspector to troubleshoot issues