problem with rpm2html

[Robert Voigt]

I want to know what's inside some rpm packages. I found rpm2html can generate 
html pages out of the contents of an rpm package.
But everytime I say
rpm2html a-package.rpm
it says
config file a-package.rpm seems invalid
I tried this with several rpms for several distributions.
Unfortunateley I can't find any documentaion on rpm2html that explains the 
commandline options.
Can anyone help me?