Exchange 2013 free/busy not seen by users in different mailbox database suddenly

Hi folks,

suddenly I have this problem that users in Maildb1 can't see free/busy information at users in Maildb2 and vice versa in my Exchange 2013 environment. Users in the same MailDB can see eatch other free/busy info, but not via databases. 

Anyone familyar with that one?

My setup is:

cas0  15.00.0775.041 (15.00.0775.041 15.0.775.41 2880833 Security issue that is described in Security Bulletin MS13-105 is resolved by an Exchange Server updateDecember 10, 2013)
cas02 15.00.0775.041 (15.00.0775.041 15.0.775.41 2880833 Security issue that is described in Security Bulletin MS13-105 is resolved by an Exchange Server updateDecember 10, 2013)

Regarding to: http://exchangeserverversions.blogspot.com/2013/01/exchange-server-2013.html (http://support.microsoft.com/kb/2880833/en-us)

mbx01 15.00.0712.024 ( Exchange Server 2013 Cumulative Update 2 (CU2)15.0.712.2407/29/2013)
mbx02 15.00.0712.024 ( Exchange Server 2013 Cumulative Update 2 (CU2)15.0.712.2407/29/2013)

Regarding to: http://exchangeserverversions.blogspot.com/2013/01/exchange-server-2013.html (http://support.microsoft.com/kb/2859928/en-us)

Thanks in advanced,

Bjarni