Can NOT apply the boundary conditions for T-Rex
 

Hi all,
I am working on a workflow to import the surface mesh made by OpenVSP to Pointwise for automating viscous meshing. An error occurred when applying the boundary conditions for T-Rex. The error says:

[ERROR: invalid objectERROR: usage (argument 2): ::pw::TRexCondition_3 apply register_or_entity_list".

As this error depends on the *.stl file imported to Pointwise, I have no idea why it happened.

Then I attempted to apply the boundary conditions for T-Rex manually and found the domains which I want to apply the boundary conditions is gray in color. That is, they can NOT be selected. (Three screenshots are added.)

So, first I want to know what causes this problem? i.e. The boundary conditions cannot be applied. Is the poor quality of the surface mesh or anything else?

Then, is there an easy way to fix this problem in Pointwise?

Thanks in advance.

P.S. The *.stl file is added for convenience. It is not water-tight with 6 Border Edges, 0 Edges > 2 Tris. (Sorry for that, but more refinement of the surface mesh will make OpenVSP crash in meshing).