MQTT vs Tinkerkit sensor Shield

Hi.
I'm working with this Arduino Client for MQTT · knolleary. 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.