Simulation stop with SetVelocityTarget()

Hello, I'm writing a plugin to control the velocity of a joint to simulate a brushless motor I try to use the SetVelocityTarget() function with the SetVelocityPID() function. The plugin compile correctly but when I publish a new message to set the velocity, the simulation stop : the model disassembles itself at the origin of the world. I already used the SetPositionTarget() with the PID and it works well. Any ideas ? Thanks