How can i export the mesh?

[pupcs]

im trying to generate an .obj file from the output of the network, but im keep getting an empty file

im doing it like this:
python run.py --training_data data/Klown.obj --n_steps 50 --save_snapshot ../output/snapshot.msgpack --save_mesh ../output/klown.obj

but it always ends up:
Generating mesh via marching cubes and saving to ../output/klown.obj. Resolution=[256,256,256], Density Threshold=2.5
01:16:09 INFO #vertices=0 #triangles=0

did anyone face the same problem?