twitter direct messages without recipient

[Vadym Khokhlov]

I have problem with parsing some direct messages. As described here:

https://dev.twitter.com/docs/api/1/get/direct_messages

JSONed direct message contains key  'recipient'. Value of this key is dictionary with information about dm's recipient. And I parsing this information like this (in python):

res_msg['receivers'] = msg['recipient']['screen_name']

But for several messages I've got error for code above: 

TypeError: string indices must be integers, not str

Why in this case msg['recipient'] is not dictionary?

How can I get screen name of recipient?

Does 'recipient_screen_name' value always contains screen name or also may be empty?