Google Maps Waypoint optimization doesn't work

I’m trying to use the google maps API with the waypoint optimization.

This is one of my examples: Link to JSON

The given optimal waypoint order is:

“waypoint_order” : [ 2, 4, 0, 6, 5, 3, 1 ]
But this is NOT an optimal route!!! what can I do?


PS: here’s the API-documentation: