Grafana forbids alert though there are no templates in my query

Grafana
1

Here’s my query :

SELECT sum("mean") 
FROM (
SELECT mean("value") from measurement 
WHERE "enrollType" = 'Desktop' 
AND "pathType" = 'Legacy'  GROUP BY "build", "page"
) 
WHERE $timeFilter GROUP BY time($__interval) fill(none)

Here’s alert config

image
image1846×468 67.1 KB

I don’t understand what is the issue here. I don’t have any variables in my query. Why can’t I set up my alert?