Query with Mulitpoint geometry: "Invalid or missing input parameters."

[JörgPossin]

I am trying to query a feature layer on my ArcGis Server withe the following code:

var queryTask = new esri.tasks.QueryTask(arcServerRESTURL + "/" + layerNumber);

var query = new esri.tasks.Query();
query.geometry = multipoint;
query.returnGeometry = true;
query.outFields = ["*"];

queryTask.execute(query, function(featureSet) {
 for (var i=0, il=featureSet.features.length; i<il; i++) {
  idList.push(parseInt(featureSet.features.attributes.id));
  if (showResult) {
   featureSet.features.setSymbol(gemeindenSymbol);
   graphicsLayer.add(featureSet.features);
  };
 }
 }
}, function(error){
 alert(error);
});

Everytime I got this error message:

Invalid or missing input parameters.

Can I do something that the query use the mulipoint as geometry type?

Regards
Jörg