export mesh file to fluent

hi...please help me

I want to export mesh file to fluent and my geometry consist of 2 volumes.

when I export this mesh under the .cas format HM report warning and fluent report warning and cann't open and read this file.

please help me how i can mesh this type of geometries for CFD analysis beacause I can mesh and import to fluent the 1 volume geometry.

if possible,send your explanation to my e-mail address.

omid.tutunchian@gmail.com

thanks so much.