[Boost-users] [program_options] How to extract option value?

In order to get the option value I have this code: options_description opd; string in; opd.add_options() ("help","Display help") ("input_file,I",value<string>(),"Input file with group division"); variables_map vm; store(parse_command_line(argc,argv,opd),vm); notify(vm); if(!vm["help"].empty()) cout<boost::bad_any_cast

' what(): boost::bad_any_cast: failed conversion using boost::any_cast

What do I wrong? -- Regards Krzysztof J.