Invalid property value

Hello community,


I have a problem when I run a simulation about particle tracing. Its about the particles in the laminar flow. I can compute the first step , laminar flow, with no problem. however after adding another physics, particle tracing, i cant compute and always receive a error message.


The error message is,
Invalid property value
-property: sphereradiusscale
"radius scale factor" is a real number.x>=0


because i can compute the first step, i think its not for the reason of the geometry. Does anybody have idea to solve this problem?


THe attachment is the pic of the problem.


best regards,