Using Rest API to List Tables Group

I am trying to use the REST api to insert rows in a Table that resides in a Shared Workspace.

I can list all the groups I can see using:

https://api.PowerBI.com/v1.0/myorg/groups

And using the relavant groupid I can list the datasets using 

https://api.PowerBI.com/v1.0/myorg/groups/{mygroupid}/datasets

but if I try and see the tables in a specific group using 

https://api.PowerBI.com/v1.0/myorg/groups/{mygroupid}/datasets/{mydatasetid}/tables

I get a 501 error : "The remote server returned an error: (501) Not Implemented."

According to this documentation updated in Feb https://msdn.microsoft.com/en-us/library/mt203556.aspx it should work.

Is this method working for other people?

Cheers,

Phil