fix for: https://issues.apache.org/jira/browse/AMQNET-311
diff --git a/src/main/csharp/Transport/Tcp/SslTransport.cs b/src/main/csharp/Transport/Tcp/SslTransport.cs
index d1fcf51..bba9c6f 100644
--- a/src/main/csharp/Transport/Tcp/SslTransport.cs
+++ b/src/main/csharp/Transport/Tcp/SslTransport.cs
@@ -244,6 +244,7 @@
                 }
 
                 X509Store store = new X509Store(name, location);
+                store.Open(OpenFlags.ReadOnly);
                 collection = store.Certificates;
                 store.Close();
             }