Exchange 2007 redirection issue

Hi,

I deployed iApp template for Exchange 2013 and it works fine. But in this environment there are legacy Exchange server (2007) and Exchange 2013 server. I modified Access policy by following instructions from this video https://www.youtube.com/watch?v=xRsUqWp1Ngs. My final result is: For Exchange 2013 everything works fine. For Exchange 2007: user tries to authenticate and enters his credential, system redirect him to legacy server and logon screen shows up again. After second authentication browser tries to enter to Exchange 2007 mailbox but it get stuck there. APM logs show that the issue occures when expression user.session.exchange comes to evaluation e.g. it says: fail to authenticate. Does anyone has any advice regarding this issue? Thanks in advance.