Hello, kemal panigoro.
Thank you for visiting Apple Support Communities.
After looking at the iCloud system status, I see there was an outage in regard to iCloud mail on April 12, 2014. I would recommend attempting to add the account again. If the issue persists, try the troubleshooting steps in the article below.
iCloud: Troubleshooting iCloud Mail
http://support.apple.com/kb/ts4002
Cheers,
Jason H.