Problem suffix DNS in Directaccess 2012

Hi,

I have 2 forests (forest 1 and forest 2). Trusts between forest are transitive.

my DA is in forest 1

DA works properly. My clients can connect via Direct Access and use resources from Forest 1.

I want my client to access ressources from forest 2.

I add suffix DNS of forest 2 and IP V4 Address of DNS Server of Forest 2 (Step 3: Infrastructure server)

Every thing seems ok, Wizard validate my ip V4 address.

I apply configuration, but after few seconds in "Operations Status" page, I have this error message:

DNS: Not working properly

Enterprise DNS servers (fd12:58f4:xxx:xxx:xxx) used by DirectAccess clients for name resolution are not responding.

I noticed that DA convert my IP V4 directly to Ip V6 Address (fd12:58f4:xxx:xxx:xxx) and I can ping IP V6 Address fd12:58f4:xxx:xxx:xxx

And of course, my client cannot access or ping any ressource of forest 2.

Any idea ?

Regards

OMSTEF