The remote server returned an error: (407) Proxy Authentication Required.- BCS

We are trying to Consume OData in BCS using an App External Content Type. The OData service that we used is http://ift.tt/1ERMRPn

We followed http://ift.tt/16JiiwQ to create app external content type.

But when we are trying to access the list we are getting below error:

"The remote server returned an error: (407) Proxy Authentication Required."

Does anyone have any idea what we are missing?

Thanks,