I may have missed this when I explained it to you before, but a Generate Alert event results in a Warning status type, so your trigger should look something like this (which I've just tested okay here):
Triggers on: Failure
Triggers task : Generate Alert
Set your threshold and some warning text to write into the log, create this trigger.
Expand the trigger and click the + to chain a new event 'email on alert'
Triggers on: Warning
Triggers task: Send Email
Add a subject and body, then add an email address into delivery->to.
If this isn't working, do you see that warning in the log? You should see something like this: