No sample peak

Hi During CHNS analysis the equipment (Vario MICRO Cube/Elementar), we got no peak for CHNS and the are of all elements where zero. The system shows the message "waiting for peak start" and then TCD detector be inactive again. The carrier gas flow per min. was 30 ml under recommended. what could it be the reason? Thanks

Equipment: Elemntar- Vario Micro cube