Msg 7391, Distributed Transactions (DTC) on SQL Server
I would imagine its either:

EXEC sp_serveroption @server = 'ServerB',@optname = 'remote proc transaction promotion', @optvalue = 'false' ;



  Use this option to protect the actions of a server-to-server procedure
  through a Microsoft Distributed Transaction Coordinator (MS DTC)
  transaction. When this option is TRUE (or ON) calling a remote stored
  procedure starts a distributed transaction and enlists the transaction
  with MS DTC.


Or could be an issue with MSDTC configuration, which is a laborious and lengthy checklist to run through, documented fully in Recommended MSDTC settings for using Distributed Transactions in SQL Server.