Tickscript does't send opsgeine alert

Hey,

I add basic script in order to send test alert to opsgeine2 account but receiving error. can you advice please?

script:

`dbrp “metric_test”.“90days”

stream
|from()
.measurement(‘cpu’)
|alert()
.crit(lambda: “usage_idle” < 10)
.message(‘Hey, check your CPU’)
.opsGenie2()
.teams(‘test’)`

errors :

ts=2019-07-24T17:28:40.652Z lvl=error msg=“error evaluating expression for level” service=kapacitor task_master=main task=memory node=alert2 err=“left reference value “usage_idle” is missing value” level=CRITICAL

thanks!