Client PlayMedia returns 200 code, but failure in body

I’m using the python PlexAPI package inside Home-Assistant.io -

I am trying to implement the playMedia command in Home-Assistant. However, when I invoke client.playMedia - it returns status 200, but with failure in the body text.

I modified the client.py file in order to see what was going on (Code: http://pastebin.com/cs1LzAUk); here is the output from that code: http://pastebin.com/UMEjKcxi. The client will stop playing whatever is currently playing, but the media being sent does not start.

Ideas?

Postman of the same request: https://pbs.twimg.com/media/CpjdwldVMAAS8dG.png:large