Poller Alert

Hello.

I have APC NetBotz-420.

I have created a poller and get the temperature in OID 1.3.6.1.4.1.5528.100.4.1.1.1.8.

Now I want to create an alert to the post when the temperature is above 15 ° C for example

I did this:

Type of Property to Monitor: Custom Node Poller

But it is in my opinion does not work

Please tell me how to create an alert

Sorry for my bad english