Access token validation failure when trying to get calendars from Office 365

     

I'm currently working on a webservice which has its own calendar and I'm trying to synchronizer this calendar with the clients Exchange calendars.  So far I've been doing tests with an outlook mail address (...@outlook.com) and it works great.


I use OAuth for authentication process redirect the client to : https://login.microsoftonline.com/common/oauth2/authorize etc ... then retrieve access and refresh token