I am trying to get route between many locations. ex A->B->C->D

I tried with A-B-C
http://map.project-osrm.org/?hl=en&loc=56.47309272,9.40375059&loc=56.45003813,9.40950667&loc=56.45236702,9.4092482 => it works correctly, we have a route

Go on I tried with B-C-D
http://map.project-osrm.org/?hl=en&loc=56.45003813,9.40950667&loc=56.45236702,9.4092482&loc=56.46042017,9.4167146 => it works correctly, we have a route

But if I tried with 4 locs A-B-C-D
http://map.project-osrm.org/?hl=en&loc=56.47309272,9.40375059&loc=56.45003813,9.40950667&loc=56.45236702,9.4092482&loc=56.46042017,9.4167146 => it returns status "207", "Can not find a route"

It seems strange and i dont know why.
Thank you