Difference between get_occurrence() and get_occurrences()?

[sambacore]

Pardon me if I'm missing something, but I've been trying to get an events occurrences, preferably for a given day.

When I use event.get_occurrence(date), it always returns nothing. But when I use event.get_occurrences(before_date, after_date), suddenly the occurrences on the previously attempted date show up.

Why won't this work with just one datetime object?