One one fluid region is generated from two STL files

mechamind

I am trying to generate two fluid regions using STL format, but only one region is generated with fuild particle filled in it.
The lines generates filled box region:
drawfilestl file="water.stl" />
fillbox x="0.1" y="0.1" z="0.2" mkbound="0">
modefill>void
point x="0" y="0" z="0" />
size x="1" y="1" z="1" />
/fillbox>

and lines generates filled sphere region:
drawfilestl file="sphere.stl" />
fillbox x="0.05" y="0.05" z="0.05" mkfluid="0">
modefill>void
point x="-1" y="-1" z="-1" />
size x="2" y="2" z="2" />
/fillbox>

But only filled box is generated when sphere.stl set of likes are called after water.stl lines. In this case sphere face is generated.