$ ./try.pl 
Can't locate WWW/Mechanize/FormFiller/Value/SUN.pm in @INC (@INC contains:
 /usr/lib/perl5/5.8.0/i386-linux-thread-multi /usr/lib/perl5/5.8.0
 /usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
 /usr/lib/perl5/site_perl/5.8.0 /usr/lib/perl5/site_perl .)
 at (eval 23) line 2.
BEGIN failed--compilation aborted at (eval 23) line 2.
        WWW::Mechanize::FormFiller::load_value_class('SUN') called at /usr/lib/perl5/site_perl/5.8.0/WWW/Mechanize/FormFiller.pm line 65
        WWW::Mechanize::FormFiller::add_filler('WWW::Mechanize::FormFiller=HASH(0x995ebdc)','dayOfWeek','SUN','on')
 called at ./try.pl line 30