Call-graph data in profile output

I'm trying to perform some statistical analysis of my Fortran program using gprof.  When I compile my files with "-p", the expected gmon.out file is created, however the profile file lacks call-graph data:

$ gprof -c -z -q myprog
gprof: gmon.out file is missing call-graph data

Is there a compiler flag I'm missing, or does the compiler not generate this information?  Version 12.0.4.191 Build 20110427

Thanks