ServiceBus Authorization rule creation always fails with "Request to a downlevel service failed"

Hi All,

I am using \packages\Microsoft.WindowsAzure.Management.ServiceBus.0.17.1-preview\lib\net40\Microsoft.WindowsAzure.Management.ServiceBus.dll

 ServiceBus Authorization rule creation always fails with {"<string xmlns=\"http://schemas.microsoft.com/2003/10/Serialization/\">Request to a downlevel service failed.</string>"}

 var tServiceBusAuthorizationRuleResponse = serviceBusManagementClient.Namespaces.CreateAuthorizationRuleAsync(name,
                         new ServiceBusSharedAccessAuthorizationRule()
                         {
                             KeyName = "Send",
                             Rights = new[] { AccessRight.Send }
                         }, CancellationToken.None);
var serviceBusAuthoriaztionRuleResponse = tServiceBusAuthorizationRuleResponse.Result;

Any Suggestions.