Fix for: https://issues.apache.org/jira/browse/AMQNET-328

diff --git a/src/main/csharp/MessageConsumer.cs b/src/main/csharp/MessageConsumer.cs
index c6e52c0..041ba74 100755
--- a/src/main/csharp/MessageConsumer.cs
+++ b/src/main/csharp/MessageConsumer.cs
@@ -781,7 +781,11 @@
                         this.session.TransactionContext.SyncRoot.ReleaseMutex();
                         this.session.TransactionContext.DtcWaitHandle.WaitOne();                        
                     }
-                }
+                    else
+                    {
+                        this.session.TransactionContext.SyncRoot.ReleaseMutex();
+                    }
+                }                
 
 			    lock(this.dispatchedMessages)
 				{
diff --git a/src/test/csharp/MessageConsumerTest.cs b/src/test/csharp/MessageConsumerTest.cs
index 82de37a..a75d9b8 100644
--- a/src/test/csharp/MessageConsumerTest.cs
+++ b/src/test/csharp/MessageConsumerTest.cs
Binary files differ