lync setup step one Error Not Available: Failure occurred while attempting to check the schema state. Please ensure Active Directory is reachable."

We have:

Server [win2k8r2](AD installed on server, DNS, ADCS,.Net 3.5),

ABC server[Win 2k8r2](Hyper v installed,3 hyper v machine are running, one is lync-server machine,other are sharepoint servers)

abc server is member server

i am installing lync server2010 Ent. on lync-server in order to install it i have installed SQL R2 on ABC on base machine.

on Lync-server (.net 3.5,iis role,file share is configured )

while i run a lync server 2010 Ent setup i am getting following error at Step 1 while preparing Ad.:

  Not Available: Failure occurred while attempting to check the schema state. Please ensure Active Directory is reachable...All server can communiacate with each other...

Prasad kambar