Why aren't my iphone calendar and laptop calendar syncing in icloud?

My iphone and laptop both are up to date with software upgrades and running on same system. The icloud calendar is selected "on" my iphone. I have entered new appointments on both laptop and iphone calendars but they are not showing up on both calendars.
Any suggestions?

do you have a macbook or a windows laptop?
if macbook, have you also selected the calendar option in the icloud system settings?

Also you can check if save your calendar meetings in your icloud calendar and not locally.