How should I select a tag value from influxdb and display in singlestat in grafana?

I have written this qeury that works in the influxdb SELECT "status_tag", "status" FROM "services_stats" WHERE ("host" = 'rockpi' AND "service" = 'docker.service') AND $timeFilter

I am interested in the string value from the tag key status_tag here. but when I try to run in the grafana I get this error: