Ex2010 shared mailbox folder won't open in OWA2013

Hi,

I've got simple lab environment:

• 2x Widnows 2008R2 + Exchange 2010sp3
• Widnows 2008R2 + Exchange 2013cu3
• 1 x test mailbox13 on 2013
• 1 x test mailbox10 on 2010

I added full access permission on mailbox10 to mailbo13 and want to open it with OWA.

I can do that by "open another mailbox..." option in another browser window but

when I want to "add shared folder..." to folder structure on the left panel:

In Outlook 2010 everything is ok and I can view two mailbox trees on the left.

CalendarFolderConfiguration looks fine and clean.

Any ideas?