Angular.js: $http request with JSON as response doesn't work

it's my first app with Angular.js and I've searched so hardly but I can't find a solution:

I've got a search form that makes a request to a web server which retrieves a JSON object; the problem is that this request fails and the error function begins.

Here my code:

$scope.queryUser = {};

    $scope.url = "http://xxxx:8080/MyApp/search.do?index=central&query=";

    $scope.search = function(query) {

         $scope.queryUser= angular.copy(query);

        // Create the http post request
        // the data holds the keywords
        // The request is a JSON request.
        $http.post($scope.url +  $scope.queryUser.value).
        success(function(data, status) {
            $scope.status = status;
            $scope.data = JSON.stringify(data);
            $scope.result = data; // Show result from server in our <pre></pre> element
            console.log(data);
        })
        .
        error(function(data, status) {
            $scope.data = data || "Request failed";
            $scope.status = status;   
            console.log($scope.data);
        });

and this is a sample response:

{"Workstation, Laptop@Workstation$$Laptop":[{"values":{"instanceid":"OI-4A35F9C31E114FBCB5B7668FC5E1FFB4","classid":"COMPUTERSYSTEM"},"index":"distributed"},{"values":{"instanceid":"OI-6A03793A658E45EE90E589D82B0D0962","classid":"COMPUTERSYSTEM"},"index":"distributed"}]}

Any suggestions?

Thanks in advance