To quickly find out why one or more triggers might not be working, right-click on the "Triggers" button to bring up the list of active triggers:
Here you will see an icon to the right of the number showing how many times each trigger has been executed. Click on this icon to view the suggestions as to why the trigger is not working. Here are possible examples:
But please note: only trigger log files give you the most comprehensive understanding of the reasons a trigger is or is not executed, for they contain a step-by-step description of every condition or a parameter the trigger has to check.