Rfxtrx and Capidi RAR801

I have a wireless thermometer Capidi RAR801 that I am unable to connect to my rfxtrx433e. RAR801 is Tellstick Net compatible. I have enabled the Oregon protocol, tried resetting the sensor but with no luck.

Any ideas how to connect the sensor?

I suppose it is not using the Oregon protocol. You can try with RFXmngr on a Windows system if the sensor is received using LaCrosse, Hideki, Rubicson or FineOffset. (select only one protocol for this testing)
If the sensor is not received it will not be supported.
See chapter 2 in the RFXtrx User Guide for the full list of supported sensors.