Thank you.
As a first step, could you run the test script posted here?
If that fails, we know there is something fundamentally wrong with what I'm trying to do.
If the tests in the test script pass but the main script in the mediafire package still can't find the files, we'll have to start looking for some other error source.
I think I have if ($ext eq "pdf") {...} somewhere in the script and that's why I lowercased the extension - I thought the case didn't matter anyway. This would be trivially easy to fix, and I don't think it could cause a problem here. If you test it with files that have a lower-case extension to begin with, then it's a non-issue, and in any case the test condition is (-e "$folder/$file1"), not (-e "$folder/${f1}.$ext") - so it shouldn't matter. The the string stored in $file1 isn't lower-cased.