not able to assign Interior
 

hey guys, i need a little help here. im trying to model a drop in 3D inside a cube in GAMBIT. I assigned the surface of the drop as an interior and generated a mesh file and exported it to FLUENT. Fluent is giving me an error message saying there is only one adjacent cell thread and it cannot be made an interior.

I thought maybe like in the 2D case if we do not specify a boundary condition GAMBIT will assign it as a default interior, but its assigning it as a wall which i donot want.

there was already a post regarding this, i tried it out but to no avail :(
Can anybody please help me out.