Hex core in HyperMesh

Hi,

I have a similar query with regard to creating Hex core in Hypermesh. I just want to create hexahedral elements and hence I use a value of 0 in Core/bound clearance option, but my hex core doesn't fill the whole geometry. Even if I include the pyramid elements there is still some gap. How do I fill the whole volume with hex core, if I am not interested in generating BL. Thank you for your help.

Regards
Madhu