It's good to start small and build, checking for problems as you go. In this case the smallness is the issue.

There's nothing "wrong" here. The full message, at least on my system with your posted code, is
Name "main::Objects" used only once: possible typo at ./handler.pl line 9.
Note that it warns "possible typo". There's nothing wrong there. Think about the future. You add to this start. It gets big. On some run Perl gives you a warning like
Name "main::Obects" used only once: possible typo at ./handler.pl line 99.
Without the warning you might spend a bunch of time looking for the problem in your code - because it is no longer functioning as expected. All because when you meant to type Objects you typed Obects. In that (all too familiar to me) scenario you become very thankful that Perl warnings will tell you about the error.