Hi Varun,
It could be a port not opened problem.
Check if the TCP port used for SQL Server of mdb DOMAIN database is opened between SQL Server hosting the mdb DOMAIN and new Enterprise.
By default the port is TCP 1433 but it could be different if it is a SQL named instance.
You could find the port number used by opening the properties of DOMAIN and go in tab Database :
Thanks.
Regards,
Jean-Yves