Verify that the notification has been sent from the E-mail Viewer screen. The E-mail Viewer screen lists all outbound e-mails/notifications along with any error messages if the notification/e-mail fails. There are separate checkboxes listing whether the E-mail or Push Notification has been sent.
The E-mail or Push Notification Error, if any, will be populated in their respective text boxes along with the selected checkboxes. All the records in the grid can be purged, if needed, by selecting a date range to purge, from the actions menu. This will remove all records from the specified date on the grid.