Claims user authentication for Enterprise portal !!!

Hi guys,

I am trying to create claims user authentication for Enterprise portal.I have followed the below link :

By this,i can create up to point 4 of Create claims-aware Enterprise Portal site: section. When I am trying point 5(execute the New-AXClaimsAwareEnterprisePortalServer cmdlet),I am getting an error in the cmdlet “The server is unavailable”.

Please help me to get out of it issue and give some solutions for the same.