How to set a severity label when Math expression use "is below"


Does Grafana support setting a severity level when the Math expression uses “is below”? I have several alerts that use “is below” but when I set the severity level using the dynamic label, the label outcome is not like my expectations.

Here I give an example:
I created an alert and set 10 as the threshold. If SUM of the column B is below 10 within 5 minutes, the alert will be fired. But, every time I got the alert notification, the label didn’t send a Critical label instead an Info label. Besides, when the alert was back to normal, the severity level would change to Critical.

I set the severity label like this:
{{if gt $values.B.Value 5.0}}Critical{{else}}Info{{end}}

Is there a way to set a severity level on that case?