what I do wrong? (tetramesh)

Hey everybody!

I'm trying to use tetramesh to mesh the dark blue part to connect the fine mesh (light blue) to the coarse mesh (yellow).

The problem is when I mesh it as one hallow solid, it meshes even the inside of it which suppose to be empty... and when i cut it in half and want to mesh it (which is the preferred way for me), it gives me this error that I don't even know what it means: 'planar boundary face angle too large'

Attached are all the screenshots showing what I described. Anyone knows what I'm doing wrong?

I use HM13 and Abaqus as a solver.

Thanks,

Maysam

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>