[PyMOL] problem in using delphi to color molecular surface

Dear Pymol users

I am trying to make an electrostatic surface with delphi in pymol. 
I loaded my protein structure and showed the surface, and then loaded the .phi file as emap,
But, once I loaded the .phi file, my molecule disappeared immediately, without any
error message. Everything seems normal, but my protein molecule is not shown. 

Has anyone using Delphi in pymol seen this before? 

Thank you
Rongjin Guan