List user groups with REST SDK returns Empty

Hi,

I'm trying to implement some of the Telligent API and I'm using REST SDK The documentation is not quite clear and it's missing some key information which sometimes keeps you busy for a long time

I use default host to connect to Telligent 10, I implemented oauth and I managed to get user information with the USER ENDPOINT

Now I'm trying to get the user groups / roles / memberships (i'm not quite sure what's the difference) and I use

GET api.ashx/v2/users/{userid}/groups.json

GET api.ashx/v2/users/{username}/groups.json

GET api.ashx/v2/groups.json?UserId=xxx

I tried with Impersonate=true or false but every time it returns an empty list. Any idea how can this be implemented ?

If I just try to return the full list of groups, it works

GET api.ashx/v2/groups.json