Cant get .NET Client running

ArgumentException: Input JSON was invalid.
ParseException: Invalid response from server

This is what I get after executing anything to the parse-server

My Initialization in Program.cs

static void Main()
    ParseClient.Initialize(new ParseClient.Configuration
       ApplicationId = "appId",
       // the serverURL of your hosted Parse Server
       Server = ""

    Application.Run(new Form1());

And for example I try to run a Cloud Function called “ping” and expect to get a “pong” return:

private void button3_Click(object sender, EventArgs e)
    ParseCloud.CallFunctionAsync<IDictionary<string, object>>("ping", null).ContinueWith(t => {
    var pong = t.Result;

Im using Parse-Server 4.2.7 and DotNetSDK 1.7.0

Ive already checked the appId and the Server Address. Its both correct and the server is running.
Also tried passing an empty Dictionary → didnt work

What am I doing wrong?
Please help me :confused:

I think the problem is your server response. Would you mind to share your cloud function code?