I have just realized that your NWChem is not linked with SCalapack, since your error message shows that the diagonalization calls are handled by the built-in Peigs library.
Could you try to link your executable with Scalapack and see if the error goes away (that's what I have seen in my NWChem 6.6 installation)? http://nwchemgit.github.io/index.php/Compiling_NWChem#Optimized_math_libraries