How send instant message to distribution group using UCMA 5.0 and C#?

Hi Support,

I am trying to integrate Microsoft Lync instant messaging using UCMA 5.0 to our web application. I am able to send and receive IM to lync user but when I create userEndpoint using distribution group email id it gives me error in 'CallEstablishCompleted' event

"A 404 (Not Found) response was received from the network and the operation failed. See the exception details for more information."

I have followed sample application "InstantMessagingCall" from msdn site.

Is there any difference in sending IM to User and Distribution Group.