os x mail sync problem

Hi

I'm using icloud in my PC, iphone, ipad and mac (OS x mountain lion).

Everything works smooth execpt mail sync in mac osx mail client does not work properly..

From some reason, the mail client does not sync with other devices and any mail that I download with osx mail client is showed as unread (though in other devices it shown as read). The same goes with flagged mail (even if you unflagged it in other devices - spacially on PC - it still shown as flagged in mail although it is shown as unflagged in all other devices including icloud web site).

Anyone has any idea how to fix it?