Events permalink: ?mc_id=1

Hi,
I have My calendar plugin on multi-site web and with “pretty permalinks”, it doesnt work, but without it, it works, however: when I click on single event (to show event details), it gives me this link – “www.domain.com/calendar/?mc_id=1” and it doesnt show event details but page called “calendar” and some not templating event details. Its not the specific post with details. I want it shows event details which I templated. Where is the problem, please?

I think it should be something like: “www.domain.com/calendar/nameofevent/?mc_id=1”. But I need this without “pretty permalinks” on.

It is very urgent, Thanks.