REST API Update StatusAssignment - Forbidden

Guys, I'm trying to update a few weeks the assignment of a particular resource. When searching the web I found Some articles from microsoft:

https://msdn.microsoft.com/en-us/library/office/jj669912.aspx#mergesyntax

On top of this article I started to develop my code. And to make the request to the service is the access denied error (404-Forbidden). Does anyone have any idea what can be?

   var updateEndPoint = oAuth.ProjectURL + "/_api/ProjectServer/EnterpriseResources('" + oAuth.User.Profile.ResourceId + "')/Assignments('" + assingment.AssignmentId + "')";

        var itemPayload = { '__metadata': { 'type': 'PS.StatusAssignment' }, 'PercentComplete': 70 };


        $.ajax({
            url: updateEndPoint,
            type: "POST",
            data: JSON.stringify(itemPayload),
            contentType: "application/json;odata=verbose",
            headers: {"Accept": "application/json;odata=verbose","X-HTTP-Method": "PATCH","If-Match": "*"
            },
            success: function (data) {
                var x = data;
            },
            error: function (data, error,a) {
                var x = error;
            }
        });