After reinstalling the oracle client on a BizTalk Server, I faced to an issue about transaction with a receive location WCF Custom:
The adapter "WCF-Custom" raised an error message.Details "Microsoft.ServiceModel.Channels.Common.ConnectionException:Unable to load OraMTS ---> Oracle.DataAccess.Client.OracleException Unable to load OraMTS
Indeed the System.Transaction in .Net Environment is converted to an Oracle transaction by the adapter and the OraMTS object (from the Oracle client) wasn’t found. This conversion is due to the following reason :
The Oracle Database adapter does not support performing transactions
on the Oracle database using System.Transaction.
The adapter supports transactions using OracleTransaction.
as we can see on msdn page
So the issue is to verify that you have correctly installed the component : Oracle Services for Microsoft Transaction Server to get the OraMTS Object.
Source :
http://seroter.wordpress.com/2008/05/16/flowing-transactions-to-oracle-using-adapter-pack/
Jérémie - an other BizTalker 