When creating NHibernate Application with two databases in c#

I have created an application with NHibernate and C# using SQL Server. This application maps two separate databases. But we are getting this error:

The MSDTC transaction manager was unable to pull the transaction from the source transaction manager due to communication problems. Possible causes are: a firewall is present and it doesn't have an exception for the MSDTC process, the two machines cannot find each other by their NetBIOS names, or the support for network transactions is not enabled for one of the two transaction managers. (Exception from HRESULT: 0x8004D02B)

We tried calling each database individually and it works. But when we access two databases together this error is coming.

As this is a proprietary application, I am not able to share the code.

Any help or pointers would be appreciated.