Currently Being ModeratedDec 7, 2012 11:52 PM (in response to ardeshirbagheri)
i believe it's because Apple is not using MobileMe anymore since the release of iCloud. So what i would recommend is going to icloud.com, logging in, click on Mail, click the settings buttons in the upper-right hand corner, hit preferences, then accounts and make sure you have a an icloud email. If not then you will need to make one.
Hope this helps,