Without any details, you're probabably not going to find any useful input. Look for errors. See where they lead.
Alternatively, give some info about your issue. Is this volume or aggregate shapshots? What makes you think the schedule has failed? Are you talking about the ONTAP level snaps, or one of the snap manager tools? Have the snaps been running, then stopped? Or just never run?
If a snap fails to create, a message should log in /etc/messages saying so and why.