streaming - FFmpeg RTSP send audio stream to Wowza

I am trying to send an audio-stream to my Wowza Cloud Service (trial account) using RTSP. This works fine using LibStreamer library for Android.

I am now trying to do the same with FFmpeg on my desktop streaming my webcam's audio.

I have tried the following command (authentication disabled on Wowza):

ffmpeg -f dshow -re -i audio="Desktop Microphone (HD-3000 - Microsoft LifeCam.)" -acodec aac -strict -2 -f rtsp -muxdelay 0.1 rtsp://52.57.81.141:1935/app-xxx/yyyyyy

FFmpeg seems to do its thing however I would have expected that the webconsole of Wowza would show "connected" when receiving the stream from FFMpeg.

Any ideas? It might actually be a problem with Wowza but I checked their forum and I couldn't find any post describing my problem.