c# - Server-side waypoint limit for Google Directions API -

i trying access 23 waypoint limit in google directions api.

based on google maps directions api standard usage limits:

2,500 free directions requests per day, calculated sum of client-side , server-side queries. 23 waypoints allowed in each server-side request, or 8 waypoints when using directions service in google maps javascript api. 50 requests per second, calculated sum of client-side , server-side queries. 

i have server api key setup referencing in request uri. google api account has billing enabled.

when try make request google directions api in asp.net mvc controller, hit max_waypoints_exceeded response because have on 8 waypoints in request. however, not using google maps javascript api. making server-side request billable account.

is there may need configure in api account? maybe not linking billing account server api key?

below request uri. maybe not requesting appropriate service?

https://maps.googleapis.com/maps/api/directions/xml?units=imperial&mode=driving&origin={0}&destination={1}&waypoints=optimize:true|{2}&key={3}