When installing graphmind and configuring the amserver endpoint + the service ressoures and calling the mydomain/endpoint always seems all right - but when creation a node with graphmind field I get the message

yhow I install graphmind, when loading I got the error message

Network status error.
  Connection: http://mydomain/ []
  Code: NetConnection.Call.BadVersion
  Description: 
  Details: 
  Level: error

What is going wrong here. My fault or a bug? -