Android phone not syncing with Google account
Recently I run two times into the above mentioned problem, and the reasons were obvious, so I share the common reasons with you:
1) Adding new calendar event on the phone
When you add a new calendar event on your phone, according to the defaults settings it is added to the local calendar on your phone which is not synchronized to your Google account. Once you have done this, you can not correct it, you have to add it again to your Google calendar, but to avoid this mistake you should always check that the appointment is added to to correct calendar.
2) The Google account not syncing at all
In this case none of the mail, calendar or contacts is syncing, you can go to your accounts, you see that synchronization is enabled for all of them, but the latest synchronization is some days old, and even if you ask for an immediate synchronization nothing happens. The reason for this in my case was that the available free space went down, and I had already a notification icon. It was a bit strange, because I had more than 15 MB free space, which should be enough for all my email, contact and calendar, but after uninstalling some applications suddenly the syncing started, and I had my latest email and calendar on my phone.
So if you have strange problems with your synchronization check this 2 things first.