CALL_EXTERNAL with F90 on an SGI

["Myron Brown" <Myron.Brown(at)jhuapl.edu>]

I'm trying to use CALL_EXTERNAL on an SGI running IRIX 6.5 to call Fortran
routines.  I have read the documentation for CALL_EXTERNAL and have looked
at the examples provided with IDL.  My Fortran code looks similar to the
examples, but I keep getting errors when I call CALL_EXTERNAL saying that it
cannot find the routine.  The file is there.  I have checked the name of the
subroutine I'm calling using 'nm'.  Is there something about doing this on
the SGI that should be implemented differently?  I'm using standard MIPS
Fortran 90 Fortran.  Any ideas?

Also, I tried calling CALL_EXTERNAL using another file instead, this time an
executable program.  Of course, it won't find an entry point, but it DID
find the file!!  What's the difference.  Both files are in the same
directory.

Myron Z. Brown
The Johns Hopkins University Applied Physics Laboratory
Myron.Brown@jhuapl.edu