When I try to save Event nothing changes

[ns1]

Hi!

We have been using JEvents for 2 years and all worked great! Recently we came across some strange problem.
We have an event, a convention, and on daily basis we are editing and updating this event, meaning we are copy-pasting its schedule, details and so on.
Yesterday and today when we insert new data and click on "Save" it returns to Event listing as if saved but it doesn't save anything that we have added.

Can you tell us where is the problem? Thank you.