siri won't schedule events and add them to my calendar

once I say yes to Siri after it makes changes to an event, Siri says "Uh-oh, there's a problem, please try again" and it won't confirm the changes are made to the event.
my iPod touch's iOS is iOS 9.3
i'll be trading it in and upgrading it to a 6th generation model in December, so if i can't find a solution to my problem, I'll just wait til December.
it will remove events no problem, but i can't makes changes to an event using Siri.
can anyone help?