ActiveSynx EXCH2010 and WAF

Hi there!
I've enabled the waf for my internal werbserver.
I added the site-path-routing for /Microsoft-Server-ActiveSync.
From an iOS6 device I'am able to add the account, and the account-data are veryfied successfully.
But no data are visible in the device and a few minutes later the mail-app reports: unable to connect to server.
Does anybody has a hint for me.
Is this an ASG-, Exchange- or iOS-problem?
I added the site-path for /ews, and the task-App of the iOS-Device works, Mail/Calender still doesn't connect.

Thanks! J.Kontny