Windows 10: Unable to sync calendars on my computers.

I've searched and googled this until I'm blue in the face but all I ever get is how to switch sync on in the settings, which is already done.
I have one Windows 7 computer (it refuses to upgrade to Windows 10 and sticks at 92% every time) and three Windows 10 computers (all upgraded from Windows 7 or Windows 8.1).

I use calendar in Office online on the Windows 7 computer and the Calendar that came with 10 on the others. At first they synced without problem but soon this stopped. Now they either do not sync (it doesn't matter which of the computers I put the appointment/event in) or they suddenly sync after a couple of days. All of the computers sign in with my Microsoft account so they should be synced anyway.

The only other thing is that when I open the calendar (especially on the Windows 7 pc) the following message appears for about 7 seconds in a dark blue box in the top right of the calendar:
"Unknown message type signal/force/abchsync" The Skype logo is also in this box and if I click on it a mini-Skype opens up to the right of the calendar with this error message shown as a Skype message. This happens whether or not Skype is loaded on any of the computers.
I've search high and low but can find no explanation of this message anywhere.

Can anyone please explain what this message means and where it comes from (What's Skype got to do with it!!!) and/or suggest any ways I might get the calendars to sync.

Many thanks for any help you can offer.

:)

 

I can not sync calendar

It did not work. My calendar (windows mail works ok) on the computer doesen´t sync with the phone. I´m still unable to tick the box on the windos mobile center that sync the calendar, contacts, notes, etc

Pelease help me!!

 

Please help - Calendars from two computers sync to my PDA but appointments on the PDA do not transfer to the computers

My PDA is a T-Mobile Wing with Windows Mobile 6 Professional.

My primary computer is an HP desktop with Windows Vista Home Premium 64-bit with Outlook 2003 and uses Windows Mobile Device Center (WMDC). I sync my e-mail, calendar, contacts, and tasks to my PDA.

My secondary computer is my wife's Gateway laptop with Windows XP Home edition, also with Outlook 2003 and uses ActiveSync 4.5. I only sync calendar and contacts with my PDA.

New contacts on my primary computer sync to my PDA and from my PDA, they successfully sync (transfer to) my secondary computer.

I hadn't used my PDA to sync to either computer for awhile, but when I did recently, I discovered that appointments on either computer's calendar would transfer to my PDA, but they wouldn't transfer from the PDA to the other computer. I used to be able to keep
both computer's calendars synced by using the PDA, but now that doesn't seem to be happening. So my PDA is up-to-date with all appointments on either computer, but the computers don't have any appointments that did not originate on that computer.

Has something changed in WMDC that I can no longer sync calendars on two computers? Why does it work with contacts but doesn't seem to work with calendar?

I would be grateful for any help and guidance that anybody could provide.