Differences between JS and .NET sdk's?

Hello!
I am currently using the JS and .NET sdk's to connect to and publish messages to a pub/sub+ instance. Initially, I was using the JS sdk and have had no problems publishing persistent messages to a topic and having a durable queue subscribed to that topic. The messages are getting properly sent and picked up by the queue and consumed on the other side. Now, I am trying to setup a .NET app to publish persistent messages to the same topic. However, upon trying to publish my message, I get the attached exception/error, which suggests that I am not allowed to publish "assured" messages.

It's possible that the scaffolding code around the TopicPublisher and associated bootstrap code I am using in the 2 apps is slightly different, but I am using the same session creation info (i.e. host, user, vpn, password) in both apps so I would think the session info should be identical. Also, if I make the tiny change of setting message.DeliveryMode in the .NET app from MessageDeliveryMode.Persistent to MessageDeliveryMode.Direct, the message publishes to the topic/queue as expected, it is just not persistent - so this seems to suggest that I have things setup correctly, otherwise. Is there different processing under the hood in the sdk's in terms of permissions and what a user is allowed to do in a given session? I tried giving that user the read and write permission to see if that would help, but it did not seem to have an effect.
Please let me know what I might be missing - I can use direct mode for the time being, but would really prefer the reliability of persistent mode in the longrun.
Thank you!
-Anthony