Unable to pass parameter to Angular service, Node.JS backend Server

I have a web app with Angular, backend server with Node.JS. The problem that I having is I press a button on Html, which invoke ng-click recall a function in controller, then, controller will recall a function in Angular services. Finally Angular services will use $http.put to Node.JS server. The problem that I facing is, the parameter "myData" unable to pass to Node.JS Server. Error message from Node.JS: TypeError: Cannot read property 'source' of undefined. My codes are as per following.

html:

<button class="btn btn-default btn-lg col-sm-2 col-sm-offset-2" ng-class="videoVGA" ng-click="myFunction('ABC')" >ABC</button>    

Controller:

 $scope.myFunction = function (data){
        switch(data){
            case "ABC":
                var myData = new Object();
                myData.source = data;
                controlProvider.serviceFunction(myData);
                break;

Service:

(function(){
    function controlProvider($http) { 
        this.serviceFunction = function(myData){
            $http.put("http://localhost:8080/v/switch", myData);
        }

    }
    controlApp.service('controlProvider', controlProvider);

})();

Node.JS:

app.put("/v/switch",function(req,res){
    console.log("Printing" + " "  + req.body.source);
    if(req.body.source === "ABC"){
        //Do something
    }
});