Split meshes

In trying to split a mesh by using a single plane mesh as the cutting object. I used the split mesh command and didn’t cut it, why could it be? any help is welcome. One is a perfect closed volume-watertight and the other one just the cutting plane, a mesh as well. Thank you in advance.

Hi Sergio - this is not Rhino’s strong point - can you please post the mesh file?

thanks,

-Pascal

Hello, thanks. The file was from a friend starting using rhino. It’s not mine and He’ll join the Forum shortly. meaning I cannot upload a .3dm file that is not mine. But thanks for your help, He might reach you soon.