I have written a small visual basic utility which references a single Fortran subroutine. The visual basic program and the Fortran subroutines live in separate projects within a single solution. Both projects were created from scratch and the !$DEC DLLEXPORT command in the latter were accepted as supplied by the compiler interface. The Visual Basic program is given the Fortran project as a Dependency. And a suitable declaration was included in the Visual Basic program to the Fortran subroutine. Everything builds OK but dies in run-time. In my first attempt, I simply placed the Fortran dll in the same folder as the VB executable.
So I tried to make the Fortran dll a reference of the VB project.. The system rejected that attempt to Add it to the references. The attached message appeared. What kind of errors (of omission?) on my part could give rise to this error?