The above  <form ...> has onSubmit="javascript: return checkform();"> AFAIU this calls a js function checkform() prior to submitting. This function may be adding extra fields to the form, e.g. "I have checked the form, fields validate, it's ok for the cgi script to process it.". By accessing the cgi script directly, you may be omitting some of these fields. For example, look at the B1=Submit field (re: Re^8: Correct link to put in my WWW:Mechanize). Where does that come from? You don't mention that field in Re^11: Correct link to put in my WWW:Mechanize. But I saw it with my browser. Is that field the important difference between a successful submission? So, you need to inspect that js function and see if and how it modifies the submitted form. Then you can call the cgi directly.

Anyway, may I suggest that you leave automation to someone who knows what they are doing lest these free resources find out that there are hundreds of failed attempts and put a captcha-wall and spoil it for the community? Not that I am the internet police or anything, just an opinion. BTW your question has nothing to do with Perl or Mech.

bw, bliako