Why can't I access ArcGIS Online analysis service via Rest API?

[ab1]

Hi,

I have an admin account for ArcGIS Online with lots of credits. When I try to access the analysis service through this url: http://analysis.arcgis.com/arcgis/rest/services/tasks/GPServer?f=pjson&token=<my token>, I get the following answer:

    {

      "error" : {

        "code" : 401,

        "message" : "You do not have permissions to use this resource.",

        "details" : [ ]

      }

    }

What is going wrong?

[ab1]

I checked for analysis privileges through this url: https://arcgistest.maps.arcgis.com/sharing/rest/portals/self?f=pjson&token=<token>  and I found that I don't have them.

I've an admin account. How can I activate spatial analysis?