How to alert for single packet?

[alchemyx]

Hello,

I am monitoring via Cacti some Very Important Link (VIL for shot ). I want to be
notified even if one error or discard shows up. I set up thold with alarm set to 0,
so in my understanding it will alert if it goes over 0, but it doesn't. One error
on a link shows as 16.38m in graphs.

All other tholds are working great as usual I just can't figure how to set up this
one.

Thank you in advance