You may want to move this discussion to the Network Performance Monitor forum.
There is already a default alert called 'Alert me when an interface goes down'. You can see the details of this alert from the 'Advanced Alert Manager' utility on the NPM server.
You should see Active alerts under the HOME > Alerts view
You should be seeing the Alerts being raised and reset for this out of the box alert in the HOME > Events view
See video #7 for a quick tutorial on alerting