Not adding event to shared calendar

I schedule appointments for three people in the office. I can see and input an event on their calendars, but it is not syncing or adding it to their calendars. Each of them have already missed appointments due to this, so this is a problem I need to figure out ASAP. I can’t figure out why I can see it on mine, but they can’t see it. 

Make sure when you add a calendar item, you are using the correct calendar–

Also, check you sync time interval settings at menu/tools/settings/general/general.  Depending on the time interval it may not sync for some time (15 minutes longer than the sync interval).

What are they using as a calendar app?  Can you see appointments they create?