Particles created by mesh/tet cann't move?

Dear LIGGGHTS user,
I have tried the example of mesh/tet which create particles from a imported tet-mesh data. i.e.
"region mesh mesh/tet file data/test.vtk scale 1. move 0. 0. 0. rotate 0. 0. 0. units box"
This example create one timestep output only. Although I enlarged the run time and more output, but I can't find any change during the whole running. The question is:
If I want to use the particles created by the mesh/tet method as a initial pack of particles, want release these particles and let them flow, is this possible?
If possible, why the particle can't move, what's modification should I do?
Any suggestion will be appreciate.

Best regards

Cheng