MQTT vs Tinkerkit sensor Shield I'm working with this http://knolleary.net/arduino-client-for-mqtt/. I'm using Arduino Uno + Ethernet shield + Tinkerkit Shield. But, if i have only Arduino Uno + Ethernet Shield, i can connect my arduino with MQTT and make publish/subscribe, but, when i put the tinkerkit shield, i lost the connection and i cannot connect any more. Any idea? Tinkerkit sensor shield is incompatible with mqtt? 

Thanks.
I think your problem is in wiring. Ethernet shield is using SPI communication, it requires pins: SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). Those pins must be left for the Ethernet shield. Information is from Arduino Uno description. 

Does your Arduino communicates with you after you plug-in Tinkerkit? If not, maybe you have a short in Tinkerkit shield.