use strict;  
use WWW::Mechanize; 
my $mech = WWW::Mechanize->new();   

my $url = "http://www.peoplebank.com/pbank/owa/arcadia.arcadiagroupcategories";

$mech->agent_alias('Mac Safari');
$mech->get($url); 
sleep(1);
$mech->click('');
sleep(2);
# upto here everything seems okay, am getting the page same as from the site.

# In this page, actually a button named "p_next" is there, but I am unable to click on this button using the below code.
$mech->click("p_next");  
# The above click will giva an error like, NO clickable input with name p_next. 
#I tried but unable to solve the Issue, dont know why its not clicking, bcoz actually the button is there.