Quote

E:\perl>perl proxy3.pl
Can't call method "find_input" on an undefined value at
C:/Perl/site/lib/WWW/Mechanize.pm line 1586 (#1)
(F) You used the syntax of a method call, but the slot filled by the
object reference or package name contains an undefined value. Something
like this will reproduce the error:

$BADREF = undef;
process $BADREF 1,2,3;
$BADREF->process(1,2,3);

Uncaught exception from user code:
Can't call method "find_input" on an undefined value at C:/Perl/site/lib
/WWW/Mechanize.pm line 1586.
at C:/Perl/site/lib/WWW/Mechanize.pm line 1586
WWW::Mechanize::click_button('WWW::Mechanize=HASH(0x1f6e8fc)', 'number',
2) called at proxy3.pl line 15