MQTT publish with Mosquitto

Hi i just checked out the MQTT client from the App-Store and build a small app to check the connectivity. i am able to subscribe to a topic but not to publish a message to the topic. i works on the command line of  my laptop but not in the app. Here the screen shut for publish a message
1 answers

no , ;-(  i switched on tracing but no message on publish, but i do get a message if i subscribe to a topic