Hello Sergio
Thank you for your reply.
The demo is the one you mentioned in your last reply in previous question.
(There is a Demo called "AndroidService" which shows this using a simple websocket client. You only must attach MQTT protocol to websocket client to allow connection to your MQTT Server.)
The probloem solved, there was an error in naming subscribed topic, due to letters wrong cases (capital and small letters)
After all, thank you for your kindnesses.
Have a good day.