Exchange 2013 setup fails

Hi,

I am trying to install Exchnage 2013 but its getting failed with error below

Error:

The local domain needs to be prepared using Setup /PrepareDomain before server roles can be installed.

For more information, visit: http://technet.microsoft.com/library(EXCHG.150)/ms.exch.setupreadiness.DomainPrepRequired.aspx

I already run prepareDomain command and it was successfull