How about reducing the code to just show your problem and to eliminate anything external that isn't pertinent to the problem.

For a start, check that the parameter values are as you expect. If they are, place $q->param('...') with a constant string. That makes it easier for use to reproduce your issue. If the parameters are not what you expect, then you have learned something :).

For test purposes use print rather than printing to a file and show us what you get and what you expect.

Remove any use lines that you don't absolutly need (except use strict; use warnings;) to show the problem.

Reduce any HTML to the minimum required to show the problem.