SetOutputToDefaultAudioDevice() gets NullException

i've wanted to try out the SSML but everytime i try to run my code i get a null exception at SetOutputToDefaultAudioDevice() .

I am using the Example Code from Microsoft:

using System;
using System.Speech.Synthesis;


namespace SSML_Test
{
class Program
{
    static void Main(string[] args)
    {
        // Initialize a new instance of the speech synthesizer.  
        using (SpeechSynthesizer synth = new SpeechSynthesizer())
        {

            // Configure the synthesizer to send output to the default audio device.  
            synth.SetOutputToDefaultAudioDevice();

            // Speak a phrase.  
            synth.Speak("This is sample text-to-speech output.");
        }

        Console.WriteLine();
        Console.WriteLine("Press any key to exit...");
        Console.ReadKey();
    }
}

I'm on .NET Core 2.0 and I've correctly added the System.Speech to my References.

Full Error Log:

System.NullReferenceException
HResult=0x80004003
Nachricht = Object reference not set to an instance of an object.
Quelle = System.Speech
Stapelüberwachung:
at 
System.Speech.Internal.ObjectTokens.RegistryDataKey.HKEYfromRegKey
(RegistryKey regKey)
at System.Speech.Internal.ObjectTokens.RegistryDataKey.RootHKEYFromRegPath
(String rootPath)
at System.Speech.Internal.ObjectTokens.RegistryDataKey.Open(String 
registryPath, Boolean fCreateIfNotExist)
at System.Speech.Internal.ObjectTokens.SAPICategories.DefaultDeviceOut()
at System.Speech.Internal.Synthesis.VoiceSynthesis..ctor(WeakReference 
speechSynthesizer)
at System.Speech.Synthesis.SpeechSynthesizer.get_VoiceSynthesizer()
at System.Speech.Synthesis.SpeechSynthesizer.SetOutputToNull()
at System.Speech.Synthesis.SpeechSynthesizer.SetOutputStream(Stream stream, 
SpeechAudioFormatInfo formatInfo, Boolean headerInfo, Boolean 
closeStreamOnExit)
at System.Speech.Synthesis.SpeechSynthesizer.SetOutputToDefaultAudioDevice()
at SSML_Test.Program.Main(String[] args) in C:\Users\User\source\repos\SSML 
Test\SSML Test\Program.cs:line 15

Does someone know what my Problem is?