Get Top Trends using App-Only Auth


According to my understanding, Get Top Trends can be called in API 1.1 using Application Only Authentication.
I implemented App-Only-Auth in my app (followed but the call to Get Top Trends results in a “400 Bad Request error”. This is although I completed steps 1&2 in the guideline page successfully, i.e. obtained the bearer token.
The Twitter documentation suggests it should be accompanied by another, more explanatory, error. However I did not get any additional error.

When I activated the authentication test in it generated the full set of authentication structure, what made me suspect the authentication method. Can the Get Top Trends be called with App-Only-Auth or not?

If App-Only-Auth is valid for this call, can you suggest why I got the error?

thanks a lot,