Your using single quotes and Perl doesdoesn't "expand" variables inside them. You could use double quotes, but that would lead to lots of escaping of the quotes you've already used. Better to us the qq{} operator. See Quote and Quote-like Operators in perlop.

print qq{<input type="button" value="Download PDF Report" onClick=$lin
+k, $download); return false;">};
[download]

Why do you go to the trouble of using those modules and then not using them?

update: s/does/doesn't/