Dear Per-Olov, First time I see this error, it could be a question of scale or lack in units consistency, change your models units, for instance work in "milimeters" instead in "meters". Best regards, Blas.
Thanks, I was a little lazy, so I select feature instead of face in radiation. No it works when i select face. Another strange thing is that i got lover temperature (-14,3 C) than ambient temperature in the results. I have set temp to +20 degress C in convection and body. /Per-Olov