Unable to create a new alert for a Vertica data source

I am a newbie to Grafana. I just read a little bit on Grafana Alerting, and this looks promising for a use case I want to achieve: I would like to generate an alert everytime a metric that I am plotting in the time series chart exceeds a certain value. First of all, is this something I can achieve with Grafana Alerting?

Further, my data source is Vertica. I read that the alerting is available for any datasource whose plugin.json has marked “true” for the backend and alerting parameters, which the Vertica plugin does have marked to true. However, when I try to create a new alerting rule, the “Add query” button is greyed out. And I see a little pop-up message “You appear to have no compatible data sources”. So I see conflicting information on whether alerting feature is supported on Vertica.

Thanks
-Ankit