GiD - How to divide volume ?

[ongyinhoe]

Dear sir,

I want to divide a 3d cube by a 2d surface. The cube is 10mx10mx10m. The diving plane is 5 m above Z=0. I divided the volume via geometry>edit>divide>volume>split

But GiD said "Could not subdivide volume, check line 15 Try again".

My questions are

1. How to identify line 15 in my model ?
2. How to divide the volume ?
3. How to check if the volume has been divided into 2

Another question is, how to model a smaller volume embedded in a bigger volume ? If I mesh them, would it create duplication of smaller volume in a bigger volume ? Where can I find the similar example ?

Model file can be downloaded at https://drive.google.com/file/d/1F4XZdfoQlP2M6O0Qaxl6QMkJTYKpF_PE/view?usp=sharing

Thank you.

Best regards,

ong