EV OWA access via ISA2006 after upgrading to EV 10.0.1 from 9.0.1

Hi,

EV OWA access via ISA2006 after upgrading to EV 10.0.1 from 9.0.1 is not working anymore, it used to work fine with 9.0.1.

ISA Server 2006 on Windows Server 2003 sp2

CAS Sever – Windows 2008 R2

Mailbox Server – Windows 2008 R2

EV Server – Windows 2008 R2

Microsoft Exchange 2010 SP2

Do we need to change anything for EV OWA to work for external use via ISA server?

EV OWA works fine internally.

Many Thanks