Problem with Solid Mapped meshing

Hi,

I tried to do solid mapped meshing of a part . I divided the whole part into small mappable regions. When seen in Mappable mode it shows the whole part is mappable  .

But when I started to mesh, it shows at 0/9 Mark mapped faces : solid 23 has no valid mappable left  with red marks shown on the part.

I tried to mesh individual volumes and found was not able to mesh 2 volumes.

What may be the reason that its shown as mappable but not able to mesh it??

How to resolve it