I am working with the module services 3 (D7) and I am calling the drupal method from a Java Client. I can login (and keep the cession in the cookie) and I can create a simple node...

But I can't set a Node Reference Field.
 
To find the way to do, I first looked to the node structure (with the reference field) in my drupal site :

     [field_presta_presta_suivi] => Array
        (
            [und] => Array
                (
                    [0] => Array
                        (
                            [nid] => 43
                        )

                )

        )


So, in my JavaClient, I created a function to reproduce this structure :


    public  static HashMap addReferenceField(String field, String language, String type_ref,Object value, HashMap node, int delta ){
			HashMap f = new HashMap();
			HashMap p = new HashMap();		
			Object[] i = new Object[delta+1];			
            HashMap val = new HashMap();
			
            val.put(type_ref, value);
			i[delta] = val;
			p.put(language, i);
			f.put(field, p);
			return f;
		}

This function is used to create a HashMap that will be add to the parameter of the service 'node.create'.

This function work with a User Refence Field (which has the same node struture), but when I used it for a node reference, the server returned "Not Acceptable".

I have already passed a lot of time on it and didn't find any example or similar case, so here my question : 
  How to you use services 3(D7) to create a node with a node reference field ?

Thank you ^^