profiling problem

I've installed GHC-5.02 (and the profiling libraries) for Windows platforms (I have Windows98 running on my machine), but everytime I try to check the heap profiling for a program, I always get an empty graph (as the one attached). I'm sure I am doing the right steps (compiling the program with "-prof -auto-all" option, executing it with "+RTS -h" and then calling hp2ps). Any suggestions? -- Andre