iphone calendar entries do not sync with iCloud?

Make sure you are entering the events on your iCloud calendar. Check Settings>Mail,Contacts>Calendar>Default Calendar to be sure you have selected the calendar listed under your iCloud account name as your default and not something else like the calendar listed under On My iPhone. Only the iCloud calendar will sync with your iCloud account.

Did you check your default calendar as I mentioned above?

Try going to Settings>iCloud and turn Calendars to Off. When prompted, choose to keep the data on your iPhone. Then reset your phone (by holding the power and home buttons at the same time until you see the Apple logo, then release). When it restarts, go back to Settings>iCloud, turn Calendars back to On, then enter a new event and see if it syncs to iCloud now.

Look through the troubleshooting steps under "General Troubleshooting" and "Troubleshooting iOS Devices" here: http://support.apple.com/kb/TS3999.